CIS user guide
Contents
1. 20 6 3 Example of the influence on the data of an inappropriate mode selection 24 icis e 26 B APPENDECA CIS DATASETS 25 iececece Sickuceh need te otcten aaa eie te sda vadnclacirscte seduce A Qe bee aec ecu cpe Uoc fecu AE 28 Doc No CAA EST UG CIS esa Issue 2 0 Date 2011 04 29 Project Cluster Active Archive Page 4 of 37 1 Introduction The CIS Cluster Ion Spectrometry experiment is a comprehensive ionic plasma spectrometry package onboard the Cluster spacecraft capable of obtaining full three dimensional ion distributions about 0 to 40 keV e with a time resolution of one spacecraft spin 4 sec and with mass per charge composition determination R me et al 2001 The Cluster Active Archive CAA aims at preserving all measurements from the four Cluster spacecraft so that they are usable in the long term by the world wide scientific community as well as by the instrument team PIs and Co Is This implies that the instrument data properly calibrated are filed together with the descriptive and documentary elements making it possible to select and interpret them Perry et al 2006 This user guide is to provide help to the CAA user in using the he CIS observations All CIS datasets available in the CAA are listed in Appendix A 2 Instrument Description The CIS package consists of two different instru2. 3 illustrates the influence that an inappropriate mode selection can have in the CODIF and HIA data when using HIA low high G side and or CODIF low high G side data in a wrong region e g high G side in the solar wind 3 2 CIS Instrument Status The overall experiment performance after about 10 years of operation in space is good The particle detection efficiency degradation due to the MCP gain fatigue mechanism Prince and Cross 1971 is moderate for the HIA instrument For CODIF the efficiency degradation is more pronounced due to the operational principle of this instrument requiring the detection of both the ion stop time of flight signal and of the electrons emitted by the carbon foil start time of flight signal plus a position signal to validate the detection of an ion When processing the raw instrument data to convert them into higher level data in physical units these efficiency degradations are compensated by the calibration values used supplied in the calibration files cf Section 4 The CODIF instrument onboard Cluster sc1 is switched off since 25 October 2004 due to an MCP high voltage anomaly The CIS experiment has been operating nominally on sc3 until the 11 November 2009 when during normal operations it was switched off by the spacecraft onboard monitoring Analysis provides evidence for a damaged electronic component after having operated several times the design lifetime of 2 years and after having recei
3. 5 eV e to 32 keV e for HIA In the presence of cold plasma at energies below the instrument energy threshold or of hot plasma at energies above the instrument upper energy limit this partial density is evidently lower than the total plasma density In the presence of hot plasma at energies above the instrument upper energy limit the result is also underestimated ion bulk velocity temperature and pressure values Spacecraft potential The instrument energy domain is always defined with respect to the spacecraft potential Spacecraft charging to a positive floating potential as can be the case in low density plasmas when the ASPOC ion emitter for spacecraft potential control is not operating Torkar et al 2001 repels the low energy ions which in these cases cannot be detected by CIS cf for example section 6 10 of R me et al 2001 and section 3 4 of Dandouras et al 2005 This effect results in a further increase of the difference between the partial density measured by CIS and the total plasma density Limitations related to sampling of ion distributions Limited energy angular resolution In addition to the finite energy range the accuracy of the computed moments is also affected by the finite energy and angular resolution of the two instruments This is in particular the case for narrow energy distributions cold plasmas or cold beams and or narrow solid angle beams CODIF is more sensitive to this effect due to its coarser energy a
4. Guide to the Cluster Science Data System DS MPA TN 0015 2002 Dandouras I V Pierrard J Goldstein C Vallat G K Parks H R me C Gouillart F Sevestre M McCarthy L M Kistler B Klecker A Korth M B Bavassano Cattaneo P Escoubet A Masson Multipoint observations of ionic structures in the Plasmasphere by CLUSTER CIS and comparisons with IMAGE EUV observations and with Model Simulations In AGU Monograph Inner Magnetosphere Interactions New Perspectives from Imaging 159 23 53 10 1029 159GM03 2005 Dandouras I A Barthe Cluster Active Archive Interface Control Document for CIS CAA CIS ICD 0001 2007 Dandouras I A Barthe E Penou S Brunato H R me L M Kistler M B Bavassano Cattaneo A Blagau and the CIS Team Cluster Ion Spectrometry CIS Data in the Cluster Active Archive CAA In Proceeding of the Cluster Workshop and CAA School Springer p 369 375 2010 Dandouras I A Barthe L M Kistler A Blagau Calibration Report of the CIS Measurements in the Cluster Active Archive CAA EST CR CIS 2009b Harvey C C AJ Allen F D riot C Huc M Nonon Latapie C H Perry S J Schwartz T Eriksson S McCaffrey Cluster Metadata Dictionary CAA CDPP TN 0002 2008 Martz C J A Sauvaud H R me Accuracy of ion distribution measurements and related parameters using the Cluster CIS experiment In Spatio Temporal Analysis for Resolving Plasma Turbulence START ESA WPP 047 2
5. HIA MAG modes HIA HS side MAG partial moments modes Inner Magnetosphere CODIF HS side MAG CODIF HS side MAG Ring Current population modes ground Modes calculated moments Inner Magnetosphere CODIF RPA Mode CODIF RPA Mode Plasmashereric population partial moments HS High sensitivity instrument side LS Low sensitivity instrument side SW modes Solar wind modes MAG modes Magnetospheric modes MSH modes Magnetosheath modes RPA mode Retarding Potential Analyser mode Doc No CAA EST UG CIS esa Issue 2 0 Date 2011 04 29 Project Cluster Active Archive Page 20 of 37 6 2 CIS Data Caveats Given the complexity of an ion spectrometer and the variety of its operational modes each one being optimised for a different plasma region or measurement objective consultation of the data caveats by the end user will always be a necessary step in the data analysis independently of the data level In addition to the CAA the CIS caveats are also available at the CIS home page at http cluster cesr fr 8000 index php page caveats amp langue en Following are some of the most important caveats which the user of the CIS data should be aware of Only partial moments measured Limited energy range The calculated density values are in reality ion partial density values in the energy domain covered by the instrument typically 25 eV e to 40 keV e for CODIF and
6. Modes BM1 BM3 and the 16 CIS Operational Modes CIS Mode Mode Name 0 SW 1 Solar Wind SW tracking Mode 1 1 SW 2 Solar Wind 3D upstreaming ions Mode 2 2 SW 3 Solar Wind SW tracking Mode 3 Doc No CAA EST UG CIS esa Issue 2 0 Date 2011 04 29 Project Cluster Active Archive Page 7 of 37 3 SW 4 Solar Wind 3D upstreaming ions Mode 4 4 SW CI Solar Wind SW tracking Data Compression Mode 1 5 SW C2 Solar Wind 3D upstreaming ions Data Compression Mode 2 RPA RPA Mode PROM PROM Operation MAG 1 Magnetosphere Mode 1 MAG 2 Magnetosphere Mode 2 10 MAG 3 Magnetosphere Mode 3 11 MAG 4 Magnetosphere Magnetosheath Mode 1 12 MAG 5 Magnetosheath Mode 2 13 MAG Magnetosphere Data Compression Mode 1 Cl 14 MAG Magnetosheath Data Compression Mode 2 C2 15 CAL Calibration Test Mode Oo Jo IN IA Table 3 1 CIS Operational Modes These 16 modes Table 3 1 can be grouped into solar wind tracking modes solar wind study modes with the priority on the upstreaming ions magnetospheric modes magnetosheath modes an RPA mode and a calibration and test mode These modes correspond to different energy sweeping schemes and different combinations of telemetry products transmitted On board calculated moments are always transmitted to the telemetry with a high time resolution 1 spin A combinati
7. SW or MAG modes 2nd priority CODIF HS side SW modes 3rd priority CODIF HS side MAG modes interference from the solar wind Cesa Project Cluster Active Archive Doc No CAA EST UG CIS Issue 2 0 Date 2011 04 29 Page 18 of 37 Magnetosheath 7 Cusp n 1st priority HIA MAG modes onboard calculated moments 2 4 priority CODIF LS side MAG or MSH modes ground calculated moments 1st priority HIA MAG modes onboard calculated moments 2nd priority CODIF LS or HS side MAG modes ground calculated moments 1st priority HIA HS side MAG modes 2 d priority CODIF LS side MAG or MSH modes 1st priority HIA HS side MAG modes 2nd priority CODIF LS or HS side MAG modes Doc No CAA EST UG CIS esa Issue 2 0 Date 2011 04 29 Project Cluster Active Archive Page 19 of 37 Outer Magnetosphere 1st priority 1st priority including plasma sheet CODIF HS side MAG CODIF HS side MAG modes ground modes calculated moments 2nd priority 2 d priority HIA MAG modes HIA HS side MAG onboard calculated moments can miss higher energy particles modes can miss higher energy particles Magnetosphere j priority 1st priority ion beams CODIF HS side MAG CODIF HS side MAG e g PSBL modes partial modes moments 2nd priority 2nd priority
8. in a wrong region It includes from top to bottom HIA data from the low sensitivity side ions in the 45 x 45 sector centred in the solar wind direction HIA data from the high sensitivity side separately for four azimuthal sectors ions arriving in the 90 x 180 sector with a field of view pointing in the sun dusk tail and dawn direction respectively omnidirectional CODIF data for H He and O ions respectively ion velocity components measured by HIA and ion densities measured by HIA and by CODIF Instrument operational mode and spacecraft telemetry mode data are also included as well as spacecraft coordinates As can be seen in the HIA mode panel at the top the instrument was initially in a solar wind upstreaming ions mode mode 3 The solar wind narrow energy beam is clearly identified in the low sensitivity side HIA spectrogram while at the same time the high sensitivity side HIA spectrogram for ions arriving from the sunward looking direction does not detect the solar wind beam This is due to the energy sweep scheme adopted during these modes that stops and freezes above the solar wind alpha particles energy as explained in section 3 1 Some high energy upstreaming ions are however visible at that time in the high sensitivity side HIA spectrograms as well as in the CODIF H spectrogram which was then operating at the high sensitivity side Note that CODIF also does not detect the solar wind beam for the same reason
9. the period up to 2008 01 03 and the HIA calibrations are covering the period up to 2007 10 01 Work is in progress for the following data periods 5 6 CIS Data Processing Software The CIS data processing software to be archived is composed of two packages e The CIS_3D_MOM software specially developed for the CAA allows the user to read the CIS Level 3 files available at the CAA and interactively calculate partial or total moments of the ion distributions for selected energy and solid angle ranges The input is 3 D ion distribution functions in CEF 2 format and in corrected for efficiency particle count rate units and the output is ion density bulk velocity pressure tensor and temperature also in CEF 2 format and in the ISR2 pseudo GSE reference frame It is written in C and it can be used for either CODIF or HIA data e The cl software written in IDL and developed initially for the CIS team It reads Level 1 CIS data and calibration files is interactive and can generate a large variety of high resolution graphics spectrograms distribution functions PADs in several physical units It can also export the results as ASCII CEF data files In addition to the CIS data this software can also read generic CDF and CEF data files for correlation studies For the cl software the user can contact Emmanuel Penou cesr fr These software packages are available as documents for installation and execution on the end user s machi
10. 29 1993 Perry C T Eriksson P Escoubet S Esson H Laakso S McCaffrey T Sanderson H Bowen A Allen C Harvey The ESA Cluster Active Archive In Proceeding of the Cluster and Double Star Symposium 5 Anniversary of Cluster in Space ESA SP 598 Noordwjik 2006 Prince R H J A Cross Gain Fatigue Mechanism in Channel Electron Multipliers Rev Sci Instrum 42 66 DOI 10 1063 1 1684879 1971 R me H C Aoustin J M Bosqued I Dandouras B Lavraud J A Sauvaud A Barthe J Bouyssou Th Camus O Coeur Joly A Cros J Cuvilo F Ducay Y Garbarowitz J L Medale E Penou H Perrier D Romefort J Rouzaud C Vallat D Alcayd C Jacquey C Mazelle C daUston E Doc No CAA EST UG CIS esa Issue 2 0 Date 2011 04 29 Project Cluster Active Archive Page 27 of 37 M bius L M Kistler K Crocker M Granoff C Mouikis M Popecki M Vosbury B Klecker D Hovestadt H Kucharek E Kuenneth G Paschmann M Scholer N Sckopke E Seidenschwang C W Carlson D W Curtis C Ingraham R P Lin J P McFadden G K Parks T Phan V Formisano E Amata M B Bavassano Cattaneo P Baldetti R Bruno G Chionchio A Di Lellis M F Marcucci G Pallocchia A Korth P W Daly B Graeve H Rosenbauer V Vasyliunas M McCarthy M Wilber L Eliasson R Lundin S Olsen E G Shelley S Fuselier A G Ghielmetti W Lennartsson C P Escoubet H Balsiger R Friedel J B Cao R A Kovrazh
11. CIS CODIF H1 1D H 1D distribution omni directional CP CIS CODIF He1 1D He 1D distribution omni directional CP CIS CODIF O1 1D O 1D distribution omni directional Ion 2D pitch angle distributions CP CIS HIA PAD HS MAG IONS Ion pitch angle distribution High sensitivity CP CIS CODIF PAD HS H1 H pitch angle distribution High sensitivity CP CIS CODIF PAD LS H1 H pitch angle distribution Low sensitivity CP CIS CODIF PAD HS Hel He pitch angle distribution High sensitivi CP CIS CODIF PAD LS He1 He pitch angle distribution Low sensitivity CP CIS CODIF PAD HS 01 O pitch angle distribution High sensitivity CP CIS CODIF PAD LS O1 O pitch angle distribution Low sensitivity Ion 3D distributions CP CIS HIA HS MAG IONS Ion 3D distribution High sensitivity Magnetospheric mode CP CIS HIA HS SW IONS Ion 3D distribution High sensitivity Solar Wind mode CP CIS HIA LS SW IONS Ion 3D distribution Low sensitivity Solar Wind mode CP CIS CODIF HS H1 H 3D distribution High sensitivity CP CIS CODIF LS H1 H 3D distribution Low sensitivity CP CIS CODIF HS He2 He 3D distribution High sensitivity CP CIS CODIF LS He2 He 3D distribution Low sensitivity CP CIS CODIF HS He1 He 3D distribution High sensitivity CP CIS CODIF LS Hel He 3D distribution Low sensitivity CP CIS CODIF HS O1 O 3D distribution High sensitivity CP CIS CODIF LS 01 O 3D distribution Low sensitivity CP CIS CODIF RPA H1 H 3D distribution RPA mode CP
12. CIS CODIF RPA He2 He 3D distribution RPA mode CP CIS CODIF RPA He1 He 3D distribution RPA mode CP CIS CODIF RPA 01 O 3D distribution RPA mode Cesa Project Cluster Active Archive Doc No CAA EST UG CIS Issue 2 0 Date 2011 04 29 Page 29 of 37 Ancillary CP_CIS MODES Instrument modes CP_CIS CODIF_CAVEATS CODIF caveats CP_CIS HIA_CAVEATS HIA caveats CP_CIS CODIF_HS_RAT_IONS CP_CIS CODIF_LS_RAT_IONS Monitor Rates High sensitivit Monitor Rates Low sensitivity CP CIS CODIF HS SEL Time of Flight selected events High sensitivity CP CIS CODIF LS SEL Time of Flight selected events Low sensitivity CP CIS CODIF HS 64M IONS Ion 3D distribution 64 m q ranges High sensitivity CP CIS CODIF LS 64M IONS Graphical Ion 3D distribution 64 m q ranges Low sensitivi CG CIS SPECTRO Ion spectrograms and moments plots CSDS Prime and Summary Parameters PP CIS Preliminary ion parameters spin resolution SP CIS Preliminary ion parameters 1 minute resolution Doc No CAA EST UG CIS esa Date 28 Date 2011 04 29 Project Cluster Active Archive Page 30 of 37 Retractable cover mechanism HER Main entrance p2 pe RN l 25 TLE a of Bi ht Section xx f er g eas AMI Figure 2 1 Schematic of the CODIF instrument Doc No CAA EST UG CIS esa Issue 2 0 Date 2011 04 29
13. DIF they are deduced from the sensitivity side selected by command and from a similar energy angle matrix as for HIA and similarly eventually reduced to a lower energy resolution Solar wind tracking modes Modes 0 2 4 They allow a precise and fast measurement 4 s ofthe ion flow parameters H He For that in the solar wind for HIA the energy sweep range is automatically reduced when the field of view of the low g section is facing the 45 sector centred in the solar wind direction This energy sweep range is adapted every spin centred on the main solar wind velocity by using a criterion based on the H thermal and bulk velocities computed during the previous spin solar wind beam tracking This allows a higher energy resolution for the solar wind beam data Solar wind upstreaming ions modes Modes 1 3 5 In these modes solar wind beam tracking is performed by HIA only once every 16 spins exact value can vary depending on mode number During the remaining 15 16 spins a broader energy sweep is used for the solar wind detection by the low g section allowing at the same time the detection of upstreaming ions by the high G section which is then looking in the anti sunward direction Detailed 3 D distributions for the solar wind low g section are then transmitted to the telemetry only during solar wind beam tracking once every 16 spins but onboard calculated solar wind moments are transmitted every spin Moreover detai
14. Date 2011 04 29 Project Cluster Active Archive Page 1 of 37 Doc No CAA EST UG CIS Cesa E 2s User Guide to the CIS measurements in the Cluster Active Archive CAA prepared by I Dandouras A Barthe and the CIS Team Cesa Project Cluster Active Archive DOCUMENT STATUS SHEET Issue Date Version 1 1 04 11 2009 Doc No CAA EST UG CIS Issue 2 0 Date 2011 04 29 Page 2 of 37 Details 1st version prepared for the CAA Peer Review Document referenced as CAA EST UG CIS Revised version following recommendations from the CAA Peer Review Version 2 0 29 04 2011 Updated instrument description Instrument status table added Updated description of CIS Level 3 data Updated Data Selection Guide Section 6 3 added Other minor updates Various updates in preparation of the 5 CAA Operations Review Various updates in preparation of the 6t CAA Operations Review Caveats section reorganised Appendix added with CIS datasets table Updated instrument modes and datasets descriptions Other minor updates Doc No CAA EST UG CIS esa Issue 2 0 Date 2011 04 29 Project Cluster Active Archive Page 3 of 37 TABLE OF CONTENTS Document Status SSS E 2 Table of CONteNtS aisina Cr r 3 Vintroducton eme nen ae E LI uL uu Lc ere ae 4 2 strument Descripti Dss aaia aeaaea aaa kaa aahi a a AN AAEE aa A 4 2 1 The CODIF CIS 1 DRSEPUITEBIR a erneut ti
15. NH1_HIA E B5 v o NHe2 HIA 41 18 8888 NH1 CODIF 1 0000 E NO1_CODIF E 94908 NHe1_CODIF BB49 NHe2_CODIF 12 00 13 00 14 00 15 00 16 00 17 00 18 00 XGSE 14 83 14 09 13 28 12 38 11 38 10 30 9 10 YGSE 1 81 1 42 1 02 0 62 0 21 0 19 0 59 ZGSE 5 530 5 72 6 12 647 6 78 7 02 7 20 DIST 15 85 15 28 14 65 13 98 13 25 12 47 11 62 Produced by CESR Printing date 16 Qct 2007 vue web new cl Figure 6 2 CIS energy time spectrogram illustrating the influence that can have on the data an inappropriate mode selection See text for details
16. Project Cluster Active Archive Page 31 of 37 t South Ecliptic Pole Figure 2 2 Schematic of the CIS 1 CODIF anodes field of view High G low g with respect to the main axes In grey are the two blind anodes not used Doc No CAA EST UG CIS Cesa E 2s Date 2011 04 29 Project Cluster Active Archive Page 32 of 37 DUAL MCP chevrons SECTOR AMPLIFIERS 32 Colle amp tors CENE Figure 2 3 Cross sectional view of the HIA instrument Doc No CAA EST UG CIS esa Issue 2 0 Date 2011 04 29 Project Cluster Active Archive Page 33 of 37 t South Ecliptic Pole i A Note Numbers arrows show the particle arrival direction for each anode Figure 2 4 Schematic of the CIS 2 HIA anodes field of view High G low g with respect to the main axes Doc No CAA EST UG CIS esa Date 28 Date 2011 04 29 Project Cluster Active Archive Page 34 of 37 Figure 3 1 Schematic of the CIS 2 HIA energy sweep scheme as a function of the instrument field of view orientation in the spin plane solar wind modes 0 5 Doc No CAA EST UG CIS esa Issue 2 0 Date 2011 04 29 Project Cluster Active Archive Page 35 of 37 Slog E 0 1 0 01 10 1 0 1 0 01 Azimuth 9 180 Figure 3 2 Schematic of the CIS 1 CODIF energy sweep scheme for solar wind modes as a function of the spin phase high G field of view orientation upper panel and low g f
17. S 3D ion distribution functions The 3 D ion distributions are given in the ISR2 pseudo GSE reference frame X sunward Z is the spacecraft axis and northward pointing They give the complete 16 azimuth x 8 elevation 128 solid angles matrix by repetition division and remove the reduction to a total of 88 solid angles in the telemetry products where adjacent solid angles near the polar directions have been binned together for some CIS telemetry products Solid angles defined in the distributions correspond to particle arrival directions direction of travel of the particle Pitch angle distribution functions In addition to the 3 D distributions pitch angle distributions PADs are also provided These are calculated on ground from the 3 D distributions and the magnetic field direction spacecraft reference frame are given in particle flux units as a function of the particle energy and pitch angle 2 D distributions and their resolution is in 16 angular sectors covering the pitch angle range from 0 to 180 Omni directional distribution functions Omni directional fluxes 1 D ion distributions as a function of energy in particle energy flux units constitute another CIS archived dataset which provides an overview of the plasma environment Ancillary data Besides these 1 D 2 D and 3 D distributions some uncalibrated CODIF data sets are also included in the CIS Level 3 data files with on board selected ion detection events MCP mo
18. ace Note that HIA data acquired in a magnetospheric mode can also suffer from partial detector saturation when in the solar wind slightly underestimated densities by a factor depending on the solar wind density and temperature Martz et al 1993 e Background noise Eventual instrument background counts due to penetrating particles from the radiation belts around perigee passes or during SEP Solar Energetic Particles events can result in an overestimation of the measured fluxes and the resulting density values This effect is stronger for HIA whereas for CODIF it is mitigated by the time of flight technique which requires both a start signal and a stop signal in the correct time of flight window to validate the detection of an ion However in the harsh environment of the inner radiation belt even CODIF suffers from such a background Figure 6 1 shows an example of background induced on the HIA top panel and CODIF bottom panel ion counting statistics due to penetrating particles from the radiation belts outer and inner e Cross talk CODIF data in the solar wind if acquired from the low sensitivity side but with the instrument operating in a magnetospheric mode can suffer from cross talk with the high counting rates of the high sensitivity side which is then saturated by the solar wind The result is then overestimated densities and underestimated velocities e lonspecies spillover and He contamination CODIF mass separated d
19. ata can suffer from spillover between neighboring mass channels He data in particular are usually contaminated by H ions resulting in over estimated He densities e O contamination CODIF O data can be contaminated by penetrating particles in the radiation belts They can also be slightly contaminated by H ions in very high H flux plasmas as for example in the magnetosheath The latter is due to occasionally two uncorrelated H ions one generating only a start time of flight signal and the other generating only a stop time of flight signal and the time difference between the two being that of an O ion Doc No CAA EST UG CIS esa Issue 2 0 Date 2011 04 29 Project Cluster Active Archive Page 23 of 37 Ion species effects on HIA Presence of ion species other than H in the HIA data results in underestimated densities and in overestimated temperatures and pressures Calibration issues Inter anode calibration errors The V term ofthe ion bulk velocity is very sensitive to the anode cross calibrations and in particular to those of the anodes looking in directions away from the spacecraft spin plane polar anodes In some cases the efficiency calibration coefficients cannot completely compensate for strongly asymmetrically decreased efficiencies of such polar anodes which results in a residual offset of Vz This is in particular the case of CODIF onboard Cluster sc3 where one MCP quadrant southward looking direction
20. e 3 D ion distribution functions are described in Appendix 2 of the CIS CAA ICD Doc No CAA EST UG CIS esa Issue 2 0 Date 2011 04 29 Project Cluster Active Archive Page 12 of 37 The onboard calculated moments correspond to the Prime Parameters from the Cluster Science Data System Daly et al 2002 on board calculated moments from the full angular and energy resolution 3 D ion distributions then reprocessed on ground total efficiency calibration adjustments coordinate transformations etc However the FGM CAA data are here used for calculating parallel and perpendicular ion temperatures In addition the ion velocity is provided in both GSE and ISR2 reference frame and the whole pressure tensor is included On board calculated moments provide 1 spin time resolution and are calculated from the full angular and energy resolution 3 D ion distributions In addition to the on board calculated moments CIS Level 2 data include also CODIF moments calculated on ground from the 3 D ion distributions H He and O These provide better calibration adjustments per anode efficiency and are thus more accurate but have a reduced time and energy resolution HIA on ground calculated moments are not supplied because the same anode calibrations would be used as for the on board calculated ones but with a degraded time energy and angular resolution no added value A software package has also been developed and is available for download at t
21. f flight measurement and the position information elevation angle of the incoming ion provided by the MCP sectoring in anodes cf Fig 2 1 In order to cover ion populations ranging from dense magnetosheath to tenuous tail lobe a dynamic range of more than 105 is required CODIF therefore consists of two sections each with a 180 field of view with geometry factors differing by a factor of 100 two different entrance grids are used one per section to reduce the incoming flux This way one of the sections will have counting rates which are statistically meaningful and which at the same time can be handled by the time of flight electronics However intense ion fluxes can in some cases saturate the CODIF instrument particularly if data are acquired from the high sensitivity side but these fluxes are measured with HIA which is less sensitive to saturation The operation of the high sensitivity side high G or HS and of the low sensitivity side low g or LS on CODIF is mutually exclusive and only one of the two sides can be selected at a time to supply data The field of view of the CODIF anodes is shown in Figure 2 2 With an additional Retarding Potential Analyser RPA device in the aperture system of the CODIF sensor and with pre acceleration for the energies below 25 eV e the range is extended to energies as low as the spacecraft potential The retarding potential analyser operates only in the RPA mode and provides an energ
22. he CAA web site allowing the user to interactively calculate partial or total moments of the ion distributions for selected energy and solid angle ranges CODIF all 4 ion species and HIA data cf section 5 6 On board calculated moments and on ground calculated moments from the 3 D ion distributions are thus complementary cf section 6 1 data selection guide The way moments are calculated from the 3 D ion distribution functions is described in Appendix 2 of the CAA CIS Interface Control Document 5 3 CIS Level 3 Data Ion distribution functions CIS Level 3 data are processed high resolution data 3 D ion distributions They are produced by correcting the Level 1 data for detector efficiencies geometric factors and other information available from the calibration tables and give measurements in several physical units in separate files e differential particle flux ions cm s t srt keV e particle energy flux keV cm s srt keV e particle phase space density ions s km e corrected for efficiency particle count rate ions st e raw particle counts number of ions per counter bin Doc No CAA EST UG CIS esa Issue 2 0 Date 2011 04 29 Project Cluster Active Archive Page 13 of 37 These datasets are constructed by joining data of the same ion species from different modes that can have different angular energy or time resolution in order to create a single dataset per ion species and per sensitivity type LS H
23. ield of view orientation bottom panel The energy freeze during the reduced energy sweeps is at about 2 keV Doc No CAA EST UG CIS esa Issue 2 0 Date 2011 04 29 Project Cluster Active Archive Page 36 of 37 CIS SAMBA SC 3 30 Jun 2008 E eV Ew LII mi 3 d rmm a ud i f Jm At id l Jl E eV VEDI GA D IRA 10 15 10 30 10 45 11 00 14 15 11 30 11 45 12 00 12 15 XGSE 1 65 1 03 0 30 0986 145 75 YGSE 2 81 2 95 2 89 2 62 2 00 1 06 0 04 ZGSE 2 58 1 77 0 86 0 07 1 02 1 82 2 35 DIST 4 16 3 57 3 03 2 65 2 44 2 56 2 93 L 16 96 8 14 4 11 2 62 2 61 5 97 34 74 ILAT 75 95 69 48 60 43 51 89 51 79 65 84 80 23 NLTS 18 72 18 07 17 59 17 23 16 87 16 38 15 02 Figure 6 1 Example of background induced on the HIA top panel and CODIF bottom panel ion counting statistics due to penetrating particles from the radiation belts Doc No CAA EST UG CIS esa Issue 2 0 Date 2011 04 29 Project Cluster Active Archive Page 37 of 37 CIS SAMBA SC 3 13 Feb 2001 16 BM3 HIA Mode 8 0 NM1 w 10000 5 9 1000 V 43 us 160 Hla 2 7 10000 xy Les c s HIA 6 8 lons 6 0 x 5 3 W lons 4 6 A 3 9 ho HIA ul long 3 2 lt 2 5 B 10 lons 18 16 BM3 CODIF Mode a NM 1 1 e contro fi is gt 10000 g Log c s gt D 2 1000 NN CODIF 6 7 W Ht 58 G 4 9 CODIF 4 0 W He 31 amp 2 2 i OM 1 3 F VxH1 HIA GSM E VyH 1 HIA GSM VzH1_HIA_GSM 100 00 id i
24. ivity low g or LS side The low g side allows detection of the solar wind and the required high angular resolution is achieved through the use of 8 sectors or MCP anodes around the spin plane 5 625 each the remaining 8 sectors having an 11 25 resolution The 180 high G side is divided into 16 sectors 11 25 each For each sensitivity side a full 4x steradian scan consisting of 32 energy sweeps is completed every spin of the spacecraft i e every 4 s giving a full three dimensional distribution of ions in the energy range 5 eV e 32 keV e The field of view of the HIA anodes is shown in Figure 2 4 HIA and CODIF are thus complementary instruments ion composition and coverage of the high energies 32 40 keV e are provided only by CODIF whereas HIA provides a higher angular and energy resolution HIA is also less prone to saturation it does not saturate in the LS side but the HS side can occasionally saturate In section 6 a table is provided to help the user select the most suitable instrument depending on the region and the ion population analysed 3 Instrument Operations 3 1 The CIS Operational Modes The CIS instruments have a large amount of flexibility either in the selection of the operational mode or in the reduction of the data necessary to fit the available telemetry bandwidth CIS can thus operate in any combination of the 6 Spacecraft Telemetry Modes 3 Normal Telemetry Modes NM1 NM3 and 3 Burst Telemetry
25. kin I Papamastorakis R Pellat J Scudder B Sonnerup First multispacecraft ion measurements in and near the Earth s magnetosphere with the identical Cluster ion spectrometry CIS experiment Ann Geophys 19 1303 2001 Torkar K W Riedler C P Escoubet M Fehringer R Schmidt R J L Grard H Arends F R denauer W Steiger B T Narheim K Svenes R Torbert M Andr A Fazakerley R Goldstein R C Olsen A Pedersen E Whipple H Zhao Active spacecraft potential control for Cluster implementation and first results Ann Geophys 19 1289 2001 Doc No CAA EST UG CIS esa Issue 2 0 Date 2011 04 29 Project Cluster Active Archive Page 28 of 37 8 APPENDIX A CIS DATASETS The CIS datasets stored in the CAA are Dataset Id Dataset Title Ion Moments CP CIS HIA ONBOARD MOMENTS Ion Moments CP CIS CODIF HS H1 MOMENTS H Moments High sensitivity CP CIS CODIF LS H1 MOMENTS H Moments Low sensitivity CP CIS CODIF HS He1 MOMENTS He Moments High sensitivity CP CIS CODIF LS He1 MOMENTS He Moments Low sensitivity CP CIS CODIF HS O1 MOMENTS O Moments High sensitivity CP CIS CODIF LS O1 MOMENTS O Moments Low sensitivity Ion 1D omni directional distributions CP CIS HIA HS 1D Ions 1D distribution omni directional High sensitivity CP CIS HIA LS 1D Ions 1D distribution omni directional Low sensitivity CP
26. led 3 D distributions from the high G section e g for upstreaming ions and or for interplanetary disturbances are included in the basic products transmitted to the telemetry Outside this 45 sector the full energy sweep range is used solar wind tracking modes and solar wind modes with the priority on the upstreaming ions i e modes 0 5 However when the field of view of the high G section is facing the 45 sector centred in the solar wind Doc No CAA EST UG CIS esa Issue 2 0 Date 2011 04 29 Project Cluster Active Archive Page 9 of 37 direction cf Fig 3 1 the energy sweep stops and freezes above the solar wind alpha particles energy to avoid a quick degradation of the MCPs by the intense solar wind beam modes 0 5 For CODIF the reduced energy sweep principle is also used during modes 0 5 when the field of view of the high G section is facing the 45 sector centred in the solar wind direction Complete energy sweeping is used in the remaining part of the spin Fig 3 2 Magnetosheath modes Modes 12 14 are like magnetospheric modes However starting from 1 November 2003 the energy sweep scheme has been redefined for CODIF With the new CODIF Magnetosheath Modes modes 12 and 14 the energy sweeps are truncated and frozen at about 2 keV for 16 out of 32 sweeps when the high sensitivity side faces the magnetosheath mainstream flow to save the MCP lifetime Caveat The example discussed in section 6
27. ments e atime of flight ion Composition and Distribution Function analyser CODIF or CIS 1 e a Hot Ion Analyser HIA or CIS 2 In addition each of the instruments in order to be able to cover a dynamic range of about 6 orders of magnitude in particle fluxes provides two different geometric factors a high sensitivity side or HS and a low sensitivity side or LS 2 1 The CODIF CIS 1 Instrument The CODIF instrument combines ion energy per charge selection by deflection in a rotationally symmetric toroidal electrostatic analyser with a subsequent time of flight analysis after post acceleration to 15 keV e Ions are selected as a function of their E q energy per charge ratio by sweeping the high voltage applied between the two toroidal hemispheres The full energy sweep with 31 contiguous energy channels is performed 32 times per spin and provides an energy range between about 25 eV e and 40 keV e In the time of flight TOF section the velocity of the incoming ions is measured which allows then the calculation of their m q mass per charge ratio Microchannel plate MCP electron Doc No CAA EST UG CIS esa Issue 2 0 Date 2011 04 29 Project Cluster Active Archive Page 5 of 37 multipliers are used to detect both the ions and the secondary electrons which are emitted from a carbon foil at the entry of the TOF section during the passage of the ions These secondary electrons give the start signal for the time o
28. nd angular resolution Doc No CAA EST UG CIS esa Issue 2 0 Date 2011 04 29 Project Cluster Active Archive Page 21 of 37 Poor counting statistics Adequate counting statistics are essential for reliable results For density calculations in the case of isotropic plasma distributions HIA hits a lower limit density value of the order of 0 01 0 02 cm CODIF continues to supply density values down to about 0 001 0 002 cm although with very poor counting statistics in these cases which do not allow a reliable calculation of the higher order moments velocity temperature and pressure Solar wind modes The entire velocity phase space corresponding to the instrument energy domain is not covered during all modes cf section 3 1 and for an example cf the spectrogram discussed in section 6 3 This is the case during solar wind modes and during some magnetosheath modes CODIF data acquired after1 November 2003 during modes 12 and 14 The result is o Incorrect HIA moment values in the magnetosheath when the instrument is in a solar wind mode modes 0 5 o Incorrect CODIF moment values when data come from the high sensitivity side and the instrument is in a solar wind mode modes 0 5 o Incorrect CODIF moment values when data come from the high sensitivity side and the instrument is in mode 12 or 14 for data acquired after1 November 2003 Eclipses During short eclipses the absence of a Sun reference pulse completely desynchronises
29. ne 5 7 CIS Data Caveats An internal caveats database containing instruments caveats for the whole mission is available at http cluster cesr fr 8000 index php page caveats amp langue en This database has been also delivered to the CAA The caveats are automatically delivered together with the requested datasets to the user if there are caveats for the requested time interval Doc No CAA EST UG CIS esa Issue 2 0 Date 2011 04 29 Project Cluster Active Archive Page 15 of 37 Cf section 6 2 of this document for the main CIS data caveats 5 8 CIS Data Quality Indexes New dataset under preparation Quality indexes for 3 datasets categories CODIF ground calculated moments and HIA onboard moments CODIF and HIA PADs CODIF and HIA 3D datasets will be delivered in separate files Doc No CAA EST UG CIS esa Issue 2 0 Date 2011 04 29 Project Cluster Active Archive Page 16 of 37 6 Recommendations 6 1 CIS Data Selection Guide The following table provides a CIS data selection guide for the CAA user which CIS datasets are the most suitable depending on the region and the ion population analysed e 1st priority indicates the most suitable datasets Following priorities indicate data that can be used if the 1st priority data are not available e g mode not selected instrument OFF etc but can be less accurate as explained in the caveats e Textin gray indicates partial moments data that the u
30. nitor rates and low angular resolution distributions in 64 m q ranges These data sets are useful for monitoring instrument performance against eventual background and ion mass species separation or for searching for minority ion species Level 3 archival files are labelled with metadata i e information that describes the dataset and its contents so as to be easily understandable by the CAA user These metadata follow the specifications given in the Cluster Metadata Dictionary Harvey et al 2008 which has been produced for the CAA project by the CAA Metadata Working Group and the CDPP the French Plasma Physics Data Centre http cdpp cesr fr 5 4 CIS Graphical Data Products The CIS graphical data archived are 6 hour energy time ion spectrograms They are pre formatted displays PNG graphic files embedded in HTML pages and they are given at two levels of resolution browsing and detailed These spectrograms are supplied separately for Doc No CAA EST UG CIS esa Issue 2 0 Date 2011 04 29 Project Cluster Active Archive Page 14 of 37 each spacecraft They are also available at http cluster cesr fr 8000 public spectro index php vue SCI 5 5 CIS Calibration Files CIS calibration files are ASCII files self documented including comments machine readable and human readable Cf section 4 about CIS calibrations and Dandouras et al 2009b At the time of this writing April 2011 the CODIF calibrations are covering
31. oett omm tetendit nia aca d itte 4 2 2 The HIA 615 2 InspEUHEDOTIE oec per t ntes tenure tute Mni Dra iab foe fono ie ture gee eec tutta re dett erba nae 5 3 Instrument Operation Siis eiaa ain a e idc c ed irt tee c I DRIN DOM E RD cR MM DUE DUE 6 3 1 The CIS Operational MOUBS a 6ieaimudel d accendi ii terii eine to t chest acest die Lett 6 3 2 CIS Instrument SEDIS uuo reru pna cece canna rto rarior EO Aaaa Eea ana Aaa rer one OS rk na EEE rau QUE eras 9 4 Measurement Calibration and Processing procedures esent 10 5 Key Science Measurements and Datasets anten oir teret rrt ratto fd Mats 11 BU ead MT c E 11 5 2 UIS Level 2 Data Jon MOMENTS acc entere Ri ueste iei tei eee 11 5 3 CIS Level 3 Data Ion distribution functions eee tnacrttrec tct tiere tea 12 5 4 CIS Graphical Data Products eere hores ctabue ceti res nk tr t ere PRA MR E Cebu Rc sE pa Rura ea rub nin 13 5 5 CIS Calibration Files uoti aca tiros e albe a uten ant nota tid ua A tut rsen eui itus 14 5 6 CIS Data Processing SOPCWOTG sd e aethere tato tti ien latet aqe nderit baud 14 bur CIS Data VM uen tele kerei aara EEA Aa aaea uud AL MEE ALD LEE 14 5 8 UIS Data Quality Indexes oeste eei tnit quta t veta ce ernie a ien ti tis lus 15 6 52 918104 V6 123 076 12 LE 0 0 acest aciouni edet nat nette dide ka diidiis aaa seid det die 16 6 1 CIS Data selection Guide se eee p ut Diet at ce I apu D um ME 16 6 2 CIS Data Ca Cc D
32. on of 2 D and 3 D ion distribution functions plus other telemetry products are transmitted in parallel to on board calculated moments with a mode dependent and product dependent time resolution Mode change is performed by time tagged commands according to the predicted plasma populations anticipated along the Cluster orbit Although during the first two years of operations 2001 2002 various CIS mode selection rules have been in use since 2003 the most commonly used modes are mode 8 MAG 1 and Doc No CAA EST UG CIS esa Issue 2 0 Date 2011 04 29 Project Cluster Active Archive Page 8 of 37 13 MAG C1 in the magnetosphere mode 12 MAG 5 and 14 MAG C2 in the magnetosheath and mode 3 SW 4 and 5 SW C2 in the solar wind Mode 10 MAG 3 is also used in the magnetosphere for providing full resolution HIA data at the expense of CODIF data as e g onboard sc1 since the end of 2004 when CODIF failed on this spacecraft cf section 3 2 The RPA mode is operated about once per month either on all spacecraft or on selected spacecraft Magnetospheric Modes Modes 8 11 13 They are relatively simple modes i e the full energy angle ranges are systematically covered For HIA the different telemetry products including moments are deduced from the 62E x 88O energy solid angle count rate matrices accumulated on the high G section and eventually reduced to a lower energy resolution by binning together adjacent channels For CO
33. ration files which correspond to the instrument particle detection efficiency evolution or other changes in the instrument Calibration files include thus parameters that have been determined during ground calibrations in vacuum test facilities and are stable through the mission e g instrument angle response electrostatic analyser constant used in the calculation of the energy sweep tables etc parameters that change gradually through the mission e g particle detection efficiencies and parameters that can be changed during the mission by command e g upload of new spin accumulation tables for 3 D ion distributions in the various modes All of them are equally important in converting raw data into physical units and are used together Doc No CAA EST UG CIS esa Issue 2 0 Date 2011 04 29 Project Cluster Active Archive Page 11 of 37 How the calibration values are used to convert particle raw counts in physical units such as particle flux or moments of the ion distribution functions is described in Appendix 2 ofthe CAA CIS Interface Control Document Dandouras and Barthe 2007 A CIS Calibration Report is also provided by the CIS team to the CAA Dandouras et al 2009b The CIS calibration files are archived at the CAA 5 Key Science Measurements and Datasets For the archival ofthe CIS data a multi level approach has been adopted The CAA archival includes processed raw data Level 1 data moments of the distribution f
34. s on the high sensitivity side suffers from a strongly decreased particle detection efficiency This asymmetric efficiency degradation amplified with time and for data acquired after 23 February 2003 it cannot anymore be corrected As a result the V velocity component is highly unreliable strong offset and the density suffers from the fact that the instrument under detects the ions in one hemisphere of the phase space Detector ageing It is accompanied by a degradation of the signal to noise ratio reduced counting statistics Calibrations accuracy Determinations of the evolution of the MCPs detection efficiency are statistical Commanding issues Operation incidents They can occasionally result for short periods in missing data products in incorrect MCP high voltage and or discriminator settings which reduce the accuracy of the collected data etc These are flagged in the caveats for specific data intervals Data acquired during instrument mode switches should be used with caution up to 2 spins from mode change Doc No CAA EST UG CIS esa Issue 2 0 Date 2011 04 29 Project Cluster Active Archive Page 24 of 37 6 3 Example of the influence on the data of an inappropriate mode selection The energy time ion spectrogram shown in Fig 6 2 gives an example illustrating the influence that an inappropriate mode selection can have in the CODIF and HIA data when using HIA low high G side and or CODIF low high G side data
35. ser can calculate for the ion population under study e g calculating the density and the velocity of an ion beam propagating within a denser ambient plasma This requires running the partial moments software by the user cf Section 5 6 esa Project Cluster Active Archive Doc No CAA EST UG CIS Issue 2 0 Date 2011 04 29 Page 17 of 37 Region or ionic plasma population Ion moments Ion distribution functions Solar wind solar wind beam Solar wind foreshock region upstreaming ions 1st priority HIA SW modes onboard calculated moments 21d priority CODIF LS side SW modes ground calculated moments 3rd priority HIA MAG modes onboard calculated moments partial saturation 4th priority CODIF LS side MAG modes ground calculated moments interference from the HS side 1st priority HIA HS side SW or MAG modes partial moments 2 d priority CODIF HS side SW modes partial moments 3rd priority CODIF HS side MAG modes partial moments interference from the solar wind Note these can be obtained only by running the partial moments software cf 5 6 s priority HIA LS side SW modes 2nd priority CODIF LS side SW modes 3rd priority HIA HS side MAG modes partial saturation 4th priority CODIF LS side MAG modes interference from the HS side 1 priority HIA HS side
36. the HIA data which become useless whereas the CODIF data are acquired using an extrapolated Sun reference pulse and are thus still usable but with a degraded azimuth accuracy During long eclipses CIS is off Errors due to onboard data compression and incomplete data transmission In order to transmit the full 3D distribution while overcoming the telemetry rate limitations a compression algorithm has been introduced which allows an increased amount of information to be transmitted This however does not always work well in all situations and partial data loss can sometimes occur partial data gaps Detector saturation contamination issues Detector saturation on measurements are sensitive to eventual detector saturation in the presence of high ion fluxes instrument dead time effects The most striking example Doc No CAA EST UG CIS esa Issue 2 0 Date 2011 04 29 Project Cluster Active Archive Page 22 of 37 is the strongly underestimated solar wind density and magnetosheath density by the CODIF high sensitivity side while the instrument is operating in a magnetospheric mode cf example given in section 6 3 However these saturation effects are phase space dependent the detector can be saturated only in a limited energy range and for particles arriving in a given solid angle where the highest counting rates occur e g solar wind beam but at the same time can supply reliable measurements in the remaining phase sp
37. the energy sweep scheme adopted during these modes cf Fig 3 2 but solar wind beam data are supplied by HIA At 12 40 UT the instrument while in the solar wind was switched into mode 12 magnetosheath mode Both instruments switched then to an omnidirectional full energy sweep scheme cf section 3 1 and the low sensitivity side of HIA ceased collecting data The solar wind beam became then detectable in the sunward looking direction spectrogram from the HIA high sensitivity side but with a lower energy resolution and in the CODIF data collected then from the high sensitivity instrument side but with a strong saturation in the solar wind beam energies Note however the ability of the CODIF high sensitivity side to detect the relatively weak fluxes of the upstreaming ion populations The energy flux of these upstreaming ions is a factor of 2000 lower than the energy flux ofthe solar wind beam ions as this beam population is measured by the low sensitivity side of HIA At 14 40 UT the spacecraft entered in the magnetosheath as revealed Doc No CAA EST UG CIS Cesa E or Date 2011 04 29 Project Cluster Active Archive Page 25 of 37 by the broader energy distribution of the detected ions bow shock heating and by the anisotropic flow shown in the four directional HIA spectrograms Doc No CAA EST UG CIS esa Issue 2 0 Date 2011 04 29 Project Cluster Active Archive Page 26 of 37 7 References Daly P W et al Users
38. unctions Level 2 data and calibrated high resolution data in a variety of physical units Level 3 data Furthermore the calibration files and high level processing software are also archived For details cf the CAA CIS Interface Control Document Dandouras and Barthe 2007 5 1 CIS Level 1 Data CIS Level 1 data are decommutated decompressed and time tagged telemetry data They are in raw instrument units no corrections for MCP efficiencies etc represent the complete CIS Telemetry and are the input for all higher level processing CIS Level 1 data together with the CIS calibration files are in particular the input files for the cl software cf section 5 6 These data are organised in one file per telemetry product spacecraft day and each file is a time series of equal length records Each data record is complete time tag product type mode info etc Data are in IEEE integers or floats 5 2 CIS Level 2 Data Ion moments CIS Level 2 data are moments of the particle distribution functions ion density velocity temperature parallel and perpendicular to the magnetic field components and pressure There are two kinds of moments available on the CAA those produced onboard and those produced on the ground On board calculated moments and on ground calculated moments are complementary as the onboard moments have better time resolution while ground moments have better calibration values The calculations of the moments of th
39. ved several times the design total radiation dose The CIS experiment onboard this spacecraft is considered as not operational any more Doc No CAA EST UG CIS esa Issue 2 0 Date 2011 04 29 Project Cluster Active Archive Page 10 of 37 The HIA instrument is switched off on Cluster sc4 On this spacecraft due to an electrostatic analyser high voltage issue the HIA energy sweep range is limited between 5 eV e and 400eV e The CIS experiment is not operational on Cluster sc2 Table 3 2 gives asummary of the CIS instrument status SC 1 SC 2 SC 3 SC 4 One deficient Normal CODIF Operations Not MCP quadrant operations until Operational cf section 6 2 Oct 2004 until switch off in Nov 2009 HIA Normal Normal Switched OFF operations operations until reduced energy Nov 2009 coverage Table 3 2 CIS Instrument Status 4 Measurement Calibration and Processing procedures Both CODIF and HIA have been very well calibrated before launch in vacuum test facilities R me et al 2001 However due to the in flight evolution of the MCP detection efficiencies as a function of time the CIS calibration files are updated regularly A calibrations catalogue file which is provided with the calibration files serves as a pointer to which calibration files to use for each data time period This catalogue file evolves in an incremental way through the mission to take into account the existence of new calib
40. y range between about 0 7 and 25 eV e with respect to the spacecraft potential 2 2 The HIA CIS 2 Instrument The HIA instrument is an ion energy spectrometer capable of obtaining full three dimensional ion distributions with good angular and time resolution one spacecraft spin HIA combines the selection of incoming ions according to the ion energy per charge by electrostatic deflection in a quadrispherical analyser with a fast imaging particle detection system This particle imaging is based on microchannel plate MCP electron multipliers and position encoding discrete anodes As for CODIF ions are selected as a function of their E q energy per charge ratio by sweeping the high voltage applied between the two hemispheres cf Fig 2 3 However with no TOF section the ion mass cannot be resolved by HIA The instrument has 62 energy channels but this is then reduced on board to a lower number mode dependent by binning together adjacent channels to fit into the allocated telemetry Doc No CAA EST UG CIS esa Issue 2 0 Date 2011 04 29 Project Cluster Active Archive Page 6 of 37 In order to cover populations ranging from solar wind and magnetosheath ions to tail lobe ions a dynamic range of more than 105 is required HIA therefore consists of two 180 field of view sections with two different sensitivities with a 20 ratio corresponding respectively to the high sensitivity high G or HS and to the low sensit
Download Pdf Manuals
Related Search