BPM16-38 - Pyramid Technical Consultants
Contents
1. 9 Strip26 22 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 The connector is compatible with a pin to pin connection to an 13200 electrometer Strip 17 is connected to channel 17 and so on up to strip 32 being connected to channel 32 BPM16 38 User Manual BPM16 38 UM 131023 Page 36 of 48 PSI System Controls and Diagnostics 11 1 3 High voltage input SHV receptacle To mate with standard SHV connector Core high voltage 2 kV max Outer screen shield at chassis GND 11 1 4 Actuator control Dsub 9 pin male PIN 9 Or Ou 6 External view on connector solder side of mating plug E Limit switch common VDC in 3 1 6 6 Limit switch out The connector 18 compatible with a pin to pin connection to the actuator control port on an 13200 electrometer When the actuator is retracted pin 5 1s connected to pin 6 When the actuator is extended in beam pin 7 is connected to pin 6 11 1 5 Redundant limit switch outputs Weidmuller 4 position 3 81 mm Two potential free contact pairs Out contacts close when the switch senses the actuator 15 retracted sensor out of beam In contacts close when the switch senses the actuator 1s extended sensor in beam BPM16 38 User Manual BPM16 38 UM 131023 Page 3 of 48 PSI System Controls2. d HV bias pA oaatasc AA ee 000 9 L3 s H sense Figure 7 Schematic installation The location of the 13200 must reconcile the conflicting requirements to keep the signal cables short for best noise performance but keep the electronics out of the radiation field A maximum cable length of 10 m is recommended Longer cables will still function but signal to noise performance will degrade and the capacitive load may introduce systematic calibration offsets Refer to the 13200 user manual for further details on cable lengths Low noise signal cables must be used to minimize noise due to cable movement and vibration These are available to special order from Pyramid Technical Consultants Inc The actuator control link to the 3200 provides the switched 24 VDC for solenoid actuation and reads back the in and out limit switches A separate redundant set of limit switches allows the same information to be sent to an independent system for example for safety interlocking The BPM16 38 operates the same whether or not this optional connection is made The BPM16 38 can be supplied with pipe fittings to suit 1 8 OD pipe for flow gas feed and return as an option FLO option Flow gas is not necessary for the sensor to function but it may be preferred in some installations where the atmosphere is humid or where large atmospheric pressure excursions ar
3. CABLE STRAIN RELIEF BRACKET 2X 2 75 CONFLAT NON ROTATABLE 36 6X 14 28 THRU EACH END 5 NM MOUNTING SURFACE 4X 12 MOUNTING HOLE Figure 1 BPM layout sensor out of beam position bellows extended Dimensions mm BPM16 38 User Manual BPM16 38 UM 131023 Page 13 of 48 PSI System Controls and Diagnostics COMP AIR IN 1 4 TUBE LIMIT SWITCH VALVE INTERFACE DB 9 MALE AUXILLIARY LIMIT SWITCH OUT WEIDMULLER 4 5 3 81mm 139 0 CATHODE STRIPS DB 25 MALE VERTICAL SENSE HORIZONTAL SENSE Wil 500 0 446 0 E 76 2 13 00 1 1524 16 00 1 VERTICAL S
4. 15 Figure 4 Ion optics standard coordinate convention Transport 16 Figure 5 BPM16 38 internal coordinate system 17 Figure 6 BPM strip numbering relative to conventional beamline coordinates for beam entering via signal connector face left and via pneumatic connection face right ecce eee eee eee e e eese eese sesane 18 Figure 7 Schematic MSEAMATIONS aa cu sacan T E EE E 20 Figure S Fixed and moving cable CONNECTIONS 3 2 42 21 Figure 9 High flex cable connecting the actuator control connector to solenoid valve 22 Figure 10 Ionization chamber signal formation 24 Figure 11 Approximate gain curve for the 16 38 protons in air at 5 1 1 26 Figure 12 Measured chamber gains and corresponding centroid and width determinations as a function of beam current of 228 MeV aun enh ate aunts 27 Figure 13 Test result extract showing residual offsets of BPM sensor eee e eere eere eene eee eee eee reet tono 28 Figure 14 Beam position in BPM sensor coordinates 29 Figure 15 Displacement of BPM body coordinates red from BPM sensor coordinates 316 30 Figure 16 Change to beamline 30 Figure 17 Ionization 31 Figure 18 Electrode a
5. 110 psi maximum clean dry air CDA or nitrogen Maximum cylinder life 1s obtained with lubricated CDA Limit sensing Dual redundant microswitch sensing of fully in and fully out positions Position reproducibility Sensor positioning in beam reproduces to 0 1 mm in actuator motion direction 0 25 mm in transverse dimension referenced to BPM reference mounting surface Position accuracy Sensor positioning in beam within 0 25 mm of BPM body mechanical centre in both axes relative to BPM referenced to BPM reference mounting surface Mechanical Insertion length 152 4 mm 6 flange face to flange face with CF flanges Orientation Operable in any orientation Vertical orientation actuator above beampipe recommended for best position reproducibility we Peet Operating environment Clean and dust free 5 to 35 15 to 25 C recommended lt 70 humidity non condensing Vibration 0 1g all axes 0 1 to 1000 Hz Shipping and storage Vacuum flanges should be sealed off and gas ports should be environment plugged 10 to 50 gt 80 humidity non condensing Vibration gt 1g all axes 0 1 to 1000 Hz IN Dimensions See figures land 2 for dimensions BPM16 38 User Manual BPM16 38 UM 131023 Page 12 of 48 PSI System Controls and Diagnostics pe
6. THE BPM 106 36 10 1 IONIZATION Poo Dcos 10 1 1 SOMON ON HRS 10 1 2 Gam canran NE Lade 10 1 3 ERE 10 2 POSITIONSREADOLUUE 10 2 1 T 10 2 2 5127715788 L ec gt 10 3 16 38 MECHANICAL ASSEMBLY eeeeeteeeee eene 10 3 1 Ionization chamber electrodes 10 3 2 GOS PO CWC 0 10 3 3 7 10 3 4 Actu Or SYS OM esses rase 11 CONNECT 11 1 3 4874 BPM16 38 User Manual BPM16 38 UM 131023 Page 2 of 48 PSI System Controls and Diagnostics 12 13 14 15 16 17 11 1 1 Verttedi sense o o erit m ise RS ERR 35 14 52 Horizontalsense is eset create in ooh eA ahh oat 36 11 1 3 H SUI te 37 11 1 4 EE CT OR eR a Re a AL ue tuu een I ELA eRe 37 11 1 5 RedundantAmmioswioloHtDUls RES sawn wed dada mt coda mU arae dde eun QUE du tU ea 37 11 2 PNEUMATIC 0 38 11 3 T 38 hs Oh P WV s DRE 39 12 1 PNEUMATIC C
7. and Diagnostics 5 6 6 6 6 11 2 Pneumatic pressure Push fit connection SMC One touch McMaster Carr push to connect for 4 od plastic hose 00 C LU Exhaust Compressed gas in 1 Exhaust Q 11 3 Fill gas Gas flow fittings are optional for customers who do not wish to operate the ionization chamber sensor in atmospheric air 1 8 NPT threaded holes are provided in the upper body of the BPM for this purpose The BPM16 38 can be ordered with the FLO option which includes suitable fittings The feed tube which passes down to the ionization chamber volume should be connected on the inside to the fitting for the incoming gas The outgoing gas 1s simply expelled from the internal gas space of the BPM The flow should be regulated and typical rates are very low lt 1 sccm BPM16 38 User Manual BPM16 38 UM 131023 Page 38 of 48 PSI System Controls and Diagnostics 12 Maintenance The BPM16 38 is designed for minimal maintenance There are two recommended preventative maintenance procedures and one adjustment that may be necessary CAUTION Radiation Do not work in the beamline area or on the BPM until a survey has been completed by a qualified radiation supervisor and the radiation is known to be at acceptable levels CAUTION Entrapment hazard Do not work on the BPM until pneumatic
8. 00000 Pa then the actual gain for another air pressure and temperature 15 given by Gain AcruAL Gain sArp 1 Pressure sArp Pressure AcruAL Temperature Temperature Temperatures must be in Kelvin pressures can be in any convenient absolute unit 10 1 3 Recombination The upper beam current measurement limit of the 10nization chamber 18 set by recombination of the ions and electrons before they can be collected on the electrodes which reduces the measured current Recombination 1s a function of the local beam current density the electric field strength the gas composition and pressure It is mitigated in the BPM 16 38 by the use of a small anode cathode gap and a relatively high bias voltage At low current densities corresponding to ion beam currents up to around 10 nA recombination is neglible and can be safely 1gnored Even at higher currents the effect on the measurement of the beam centroid and width 1s comparatively little affected The BPM16 38 has been tested with 1 kV bias at beam currents up to 35 nA and shown negligible difference in the computed beam parameters PAUP 9 9 9 el C 9 e Centroid width mm 15 20 25 Beam current nA 9 V gain Hgain 9 Centroid Width Figure 12 Measured chamber gains and corresponding centroid and width determin
9. 3 Page 42 of 48 PSI System Controls and Diagnostics 13 Fault finding The BPM16 38 is designed to give you trouble free service We expect that a simple replacement policy will be followed for any units that fail on a beamline and that failed units will be returned to Pyramid for refurbishment However the following fault finding 1s provided to help decide whether a BPM should be exchanged and to guide repairs for customers who do not have a service arrangement Actuator does not Insufficient pneumatic Check pressure Use correct pressure move pressure 75 to 110 psi Mechanism 15 stuck Remove pneumatic Maintain mechanism pressure and attempt as necessary to move manually disconnected connected and secure Cables or pipes are Visual inspection Ensure all incoming snagging cables and services allow free actuator movement in all operating orientations Solenoid failure 24 V across the Replace solenoid as solenoid Solenoid necessary magnetic field detectable Flow restrictors set Check incoming gas Adjust restrictors as incorrectly pressure necessary Limit switches not Switches out of Visual inspection Adjust and secure reading as expected position microswitches so that they close within 2 to 4mm of the end of travel Switches faulty Disconnect actuator Replace switch as and check switch necessary re set function with a position DVM Error in position Mechanism not Visual inspecti
10. BPM16 38 Beam Position Monitor User Manual Pyramid Technical Consultants Inc 1050 Waltham Street Suite 200 Lexington MA 02421 USA US TEL 781 402 1700 FAX 781 402 1750 EMAIL SUPPORT PICUSA COM Europe TEL 44 1273 492001 PSI System Controls and Diagnostics 1 Contents 1 CONTENTS ec 2 FIGURES c 3 SAFETY INFORMA TION 4 MODELS 5 SCOPE OE SUPPLY och ebrei n thiet ci V ord c e eoe DE 6 OPTIONAL HM UU C GERPEXDOUTDS 77 7 6 2 SIGNAL CABLES AND CABLE 08 7 INTENDED USE AND KEY FEATURES T INDIENDEDUSE ie 1 2 KEY PEA PORES rat darting Mire d NE 8 SPECIFICATION L 9 INSTALLATION mc Ob PREPARATION AND TANDING tS Een iu 92 3550 98 080 8 utu a a Sone wee a 9 2 1 Coordinate Oz Bent drec ON ate icici ee DOES ceci eed 925 Rotal OV MCT OM CS CABLING AND 9 3 1 CONOC 932 Cable and pipe arrangement 9 3 35 Alignment and connection to vacuum beamline eee OA 10 AN OVERVIEW OF
11. ENSING HORIZONTAL SENSING Figure 2 BPM layout continued sensor out of beam position bellows extended Dimensions mm BPM16 38 User Manual BPM16 38 UM 131023 Page 14 of 48 PSI System Controls and Diagnostics 9 Installation 9 1 Preparation and handling The BPM16 38 is shipped as a vacuum tested clean assembly Do not remove protective covers until the unit can be mounted in its operating position in a clean dry area Use gloves if you might touch any vacuum surfaces Take care to protect knife edges on CF flanges or sealing surfaces on KF flanges Similarly any preparation or service work must be carried out in a clean dry environment CAUTION Entrapment hazard Once pneumatic pressure has been connected there is a risk of unexpected movement of the actuator Exercise due care 9 2 Mounting The BPM16 38 should be mounted via the reference face on its base as this 1s where the sensor position is referenced A pattern of four M6 threaded holes is provided on a precision machined surface The weight of the device should be taken via this mounting not via the beamline flanges The mounting must be aligned accurately with the beamline optical elements rigid and not subject to vibration Depending upon your application you may require that the mount provides position adjustment in the two transverse axes so that the BPM can be adjusted relative optical elements in the beamline to remove physical
12. YLINDER LUBRICATION 39 12 1 1 PONE LE OT AINE LER 39 12 2 VACUUM BELLOWS REPLACEMENT 0ccsscsccecceccscescecceccceccsccscscsccscceccscscscceccecssceseecescescsscssescescescescescuss 40 12 2 1 Ee 41 12 3 MICROSWITCH ADJUSTMENT ono eei ooa totos a uve e Led b 41 12 3 1 PrO U UTO RC REATUS ER 41 12 4 SPARE DABIS LEM ELLA Loci eth Lo 41 a 43 RETURNS 5 SPOR e Eco 46 uen c IM MI CEDE MI ME e 47 REVISION HISTORY d Ere eo eos dense duce de Pep eu P ea ced etos 48 BPM16 38 User Manual BPM16 38 UM 131023 Page 3 of 48 PSI System Controls and Diagnostics 2 Figures Figure 1 BPM layout sensor out of beam position bellows extended Dimensions mm 13 Figure 2 BPM layout continued sensor out of beam position bellows extended Dimensions mm 14 3 BEM Mounties LICE ici cn ccsscesteddecazscacasesiesdaccencecitessasssecetasasestacsecccatassnesaccsacdere Ra
13. athode spacing each axis Readout strip geometry 16 strips equal width 2 38 mm on 2 534 mm pitch Readout strip orientation Horizontal sensing strips sensing orthogonal to the axis along the centre of the vacuum bellows Vertical sensing strips sensing in the axis along the centre of the vacuum bellows Vacuum High vacuum 1 e 8 mbar or greater Bakeout Maximum bakeout 70C with screening of the electrical components and forced gas cooling of the sensor volume Stainless steel aluminium alloy Viton O ring seals Edge welded stainless steel rated lifetime gt 100 000 cycles Beam path windows 50 um stainless steel foil diffusion bonded Beampath materials Layers 1 50 um stainless steel foil entrance window 2 10 8 mm fill gas 3 152 um FR4 fiberglass epoxy with 17 3 um gold flashed copper cathode strips 4 6mm fill gas active volume 5 152 um FR4 fiberglass epoxy with 17 3 um gold flashed copper anode planes each side 6 6 mm fill gas active volume 7 152 um FR4 fiberglass epoxy with 17 3 um gold flashed copper cathode strips BPM16 38 User Manual BPM16 38 UM 131023 Page 11 of 48 PSI System Controls and Diagnostics 8 10 8 mm fill gas 9 50 um stainless steel foil exit window Actuator Pneumatic dual acting cylinder with DC solenoid control NE Solenoid valve Coil 24 VDC 50 mA DC voltage applied holds the sensor in the beam path Pneumatic pressure 75 psi minimum
14. ations as a function of beam current of 226 MeV protons BPM16 38 User Manual BPM16 38 UM 131023 Page 27 of 48 PSI System Controls and Diagnostics 10 2 Position readout The strip pitch of the BPM16 38 5 2 534 mm is relatively small compared to the beam width for the intended application so that you will see signal on three strips at least You can then use peak fitting or centre of mass calculation to determine the position of the peak to much less than one strip width typically 1096 of the strip width or less for normal beam currents and noise levels A centre of mass calculation CoG 1s simple to calculate and makes no assumptions about the shape of the peak However it 1s unreliable 11 the whole peak 15 not included or if excess background noise or offset 18 included A fit to a Gaussian 1s often the best solution Pyramid real time controller products include fast algorithms for peak fitting and centroid finding 10 2 1 Beam centroid The sensor strip geometry is controlled to high accuracy by the use of precision PCB manufacturing techniques The centre of the pattern 15 between the eighth and ninth strips in each axis with the strips numbered from 1 to 16 vertical and 17 to 32 horizontal Thus in a perfect system with no offsets a perfectly centred beam would give a centroid reading of 24 500 strips in X and 8 5 in Y which you would typically translate as a physical position of 0 000 0 000 mm If you determine a peak p
15. d of its working life you must dispose of it in accordance with local regulations in force If you are disposing of the product in the European Union this includes compliance with the Waste Electrical and Electronic Equipment Directive WEEE 2002 96 EC Please contact Pyramid Technical Consultants Inc for instructions when you wish to dispose of the device BPM16 38 User Manual BPM16 38 UM 131023 Page 47 of 48 PSI System Controls and Diagnostics 17 Revision History The release date of a Pyramid Technical Consultants Inc user manual can be determined from the document file name where it is encoded yymmdd For example 210 UM 080105 would be a B10 manual released on 5 January 2008 BPM16 38 UM 120420 First general release 16 38 UM 130521 Added information on gain curves and temperature and pressure correction BPM16 38_UM131023 Added information and picture for cable strain relief Corrected gain temperature and pressure correction equation BPM16 38 User Manual BPM16 38 UM 131023 Page 48 of 48
16. d safe by a qualified radiation supervisor Only Service Personnel as defined in EN61010 1 should attempt to work on the disassembled unit and then only under specific instruction from Pyramid Technical Consultants Inc Some of the following symbols may be displayed on the unit and have the indicated meanings Direct current Earth ground terminal Protective conductor terminal Frame or chassis terminal 1 phe Equipotentiality Supply ON C Supply OFF CAUTION RISK OF ELECTRIC SHOCK CAUTION RISK OF DANGER REFER TO MANUAL N CAUTION ENTRAPMENT HAZARD BPM16 38 User Manual BPM16 38 UM 131023 Page 6 of 48 PSI System Controls and Diagnostics 4 Models BPM16 38 Beam position monitor with sixteen sensing strips and 38mm sensing length in each axis With fixed tapped CF Conflat 2 34 inch DN40 flanges CF With fittings for flow gas operation Example BPM16 38 CF FLO BPM with CF flanges and in out flow gas fittings BPM16 38 User Manual BPM16 38 UM 131023 Page of 48 PSI System Controls and Diagnostics 5 Scope of Supply BPM16 38 model as specified in your order Four pin Weidmuller mating connector for redundant limit switch connection USB memory stick containing BPM16 38 User manual Test data Optional items as specified in your order BPM16 38 User Manual BPM16 38 UM 131023 Page 8 of 48 PSI System Controls and Diagnostics 6 Optional Items 6 1 Readou
17. d start operate in the proportional regime where the signal 1s increased greatly by electron avalanching This regime 1s generally avoided in high energy ion beamlines because it 1s less stable and the chamber is more prone to degradation from beam exposure Although the readout strips on the cathodes are separated by small gaps all the charge arriving at the cathodes 1s routed by the electric field onto the strips Therefore you can safely assume that the effective strip width 1s the same as the strip pitch and the conversion to physical units 1s given by multiplying a result in strips by the strip pitch BPM16 38 User Manual BPM16 38 UM 131023 Page 24 of 48 PSI System Controls and Diagnostics 10 1 2 Gain calibration The energy to produce an ion electron pair 18 almost constant for a given target species and very small compared to the energy carried by the ion hence the minimal effect on the beam Air 36 4 eV Oxygen gas 32 2 eV 26 3 eV 42 7 eV The amount of ionization per ion in the gas filling of the BPM ionization chamber depends upon the gas composition essentially constant 11 atmospheric air is used the distance travelled through gas the pressure of the gas and to a small extent the energy of the ion If the factors mentioned above are fixed by control or by calibration for example against a Faraday cup collector then the effective gain of the 10nization chamber chamber signal 10n beam current is known a
18. e common BPM16 38 User Manual BPM16 38 UM 131023 Page 20 of 48 PSI System Controls and Diagnostics 9 3 2 Cable and pipe arrangement Give careful attention to the routing of cables and pipe that connect to the BPM AII the connections that make to the moving upper body should be routed so that the movement of the cable or pipe when the actuator moves is allowed for without any strain being placed on the connections A strain relief bracket is provided for the signal and HV cables and the pneumatic feed pipe may also be routed via this point Do not tie the moving signal and high voltage and non moving actuator control cables together within metre 3 of the BPM There should be no tendency for the cable to the non moving part to move during actuation Failure to observe this precaution may result in failure of the actuator connection due to flexing Use strain relief bracket for moving cables 1 Fixed actuator cable not tied to moving cables Adequate excess to allow for cable movement Figure 6 Fixed and moving cable connections BPM16 38 User Manual BPM16 38 UM 131023 Page 21 of 48 PSI System Controls and Diagnostics The flexible cable connection between the actuator DSub connector on the static part of the BPM and the solenoid valve must also be allowed to flex freely without risk of interference with other cables or services Pay particular attention to this if the BPM is rotated out of the v
19. e sensor will make no difference to the reading At and below the low end of the specification proton energy range you may start to see the beam width apparently greater than it actually 1s 1n the downstream chamber due to scattering in the entrance window and upstream chamber This will have negligible effect on the centroid computation If you use low energy X rays to test the BPM on the bench then you will see less integrated signal from the downstream half of the sensor due to absorption 9 2 3 Rotation orientation The BPM will operate in any rotation orientation rotation about the beam axis to facilitate use on beamline gantry systems The position reproducibility and accuracy are guaranteed for mounting with the actuator vertical in the absolute sense either above or below the beamline Note that the terms horizontal sensing and vertical sensing lose their absolute meaning if the beamline or the BPM 15 rotated Usually we refer to horizontal and vertical relative to the nearest dipole magnets figure 4 Beamline optics that use dipole quadrupole and sextupole elements in standard relative orientations preserve the independence of the beam envelope trajectory in X and Y This means we can look at the progression of X profiles along a sequence of BPMs independently of the Y profiles If a BPM needs to be mounted at some arbitrary rotation angle to the local beamline coordinate system then readout becomes complicated and the data ha
20. ents in Measurement Category I as defined in the standard CAUTION Entrapment hazard The BPM is moved using pneumatic pressure during normal operation There is a risk of fingers being trapped in pinch points Never place body parts near the device when pneumatic pressure is present CAUTION High voltage High voltage must be provided to this device for correct operation The high voltage is not exposed in the correctly assembled unit A voltage of up to or 1000 V DC at 1 0 mA maximum is supplied to the BPM via the SHV connector The hazardous live voltages delivered to the BPM are not accessible under the definitions of EN61010 but may nevertheless give a noticeable shock if misuse were to lead you to come into contact with them The user must therefore exercise appropriate caution when servicing the device and when connecting cables Power should be turned off before making any connections The body of the BPM should be grounded via its connection to the customer s beamline and or mounting If this 1s not the case or if local regulations require a safety ground must be securely connected to the ground lug on the case CAUTION Radiation After use in a high energy particle accelerator beamline the BPM may become activated Do not BPM16 38 User Manual BPM16 38 UM 131023 Page 5 of 48 PSI System Controls and Diagnostics work on the device or move the device from a controlled area until 1 has been surveyed and declare
21. ertical or would be rotated by a beamline gantry rotation Figure 9 High flex cable connecting the actuator control connector to the solenoid valve 9 3 3 Alignment and connection to vacuum beamline Each BPM is factory tested for sensor positioning accuracy relative to the reference mounting surface and the test data includes values for the residual offset 1n horizontal X and vertical Y axes The errors will be less than 0 25 mm in X and Y When you install the BPM you may wish to compensate these small residual errors 11 an adjustable mount permits it or simply include the offsets 1n the software calibration of the sensor response The BPM must be surveyed and aligned relative to the optical components of the beamline the magnets not to the vacuum pipe Generally the BPM16 38 must therefore be connected to the beam pipe via flexible sections on either side The exception would be in beamlines where vacuum chambers are designed to be precision aligned to magnet pole pieces See section 10 2 1 for more information on how to read out beam position with appropriate corrections for residual offsets BPM16 38 User Manual BPM16 38 UM 131023 Page 22 of 48 PSI System Controls and Diagnostics 9 4 Vacuum force When the BPM16 38 is under vacuum atmospheric pressure will try to contract the bellows and thus move the sensor into the beam path This force 18 overcome by the pneumatic pressure in normal operation The default posit
22. hown transparent in the following figure Figure 19 Gas pocket and foil windows Thin stainless steel foil windows allow the passage of the beam They are diffusion bonded to the housing and should require no maintenance for the life of the BPM It is possible to assemble the BPM with the gas pocket removed if required for alignment checking The crosshairs on the backs of the cathodes are then visible 10 3 3 Vacuum housing The gas pocket moves within the vacuum housing At the end of travel in the extended position it engages on precision alignment pins to bring it into close alignment to the vacuum housing for BPM16 38 User Manual BPM16 38 UM 131023 Page 32 of 48 PSI System Controls and Diagnostics the X axis The housing includes the precision mounting face Stub tubes with alternative vacuum flanges can be mounted to suit the beamline standard Figure 21 Vacuum housing with sensor retracted out of beam position BPM16 38 User Manual BPM16 38 UM 131023 Page 33 of 48 PSI System Controls and Diagnostics 10 3 4 Actuator system The vacuum housing is stationary and the pneumatic actuator bears on it to move the sensor gas pocket spindle and the whole upper part of the assembly relative to it An edge welded bellows maintains vacuum while allowing the motion Sensor connections pass up through the bellows and are terminated on bulkhead connectors Dual microswitches make when the movement is within 4 mm of the end of
23. ion for the actuator solenoid un energized 1s for the sensor to be clear of the beam so you should be aware that this condition will not be met if pneumatic pressure 1s lost BPM16 38 User Manual BPM16 38 UM 131023 Page 23 of 48 PSI System Controls and Diagnostics 10 An Overview of the BPM16 38 10 1 lonization chambers 10 1 1 Signal formation High energy ions pass through matter with relatively small lateral scattering and energy loss but nevertheless leave a trail of ionization behind In the ionization chamber the free charge that is created 1s separated by the applied bias voltage with the positive air ions moving to the cathodes which are grounded at the virtual earths of the readout preamplifiers and the electrons or negative ions formed by electron capture moving to the anode The resulting small current is measured by the readout electronics The current from an individual 1 is too small to measure but for beam currents of a few 1075 of pA or more the aggregate current be measured by sensitive electrometer electronics Cathode Anode Cathode um 4 4 Beam ion te te Tt td _ 7 747 toc fy gt V pw WV Pre amp Pre amp Figure 10 Ionization chamber signal formation The ionization chamber uses a parallel plate geometry to provide uniform gain over its active area At higher applied bias voltages and with field intensifying geometry such as thin wires or points the chamber woul
24. ling and offsets included and store this in a software data file linked to the particular BPM The beam centroid calculation will them return directly a value in beamline coordinates 10 2 2 Beam width Conversion of computed beam width to physical units is simply a matter of multiplying the width computed in strips to mm by multiplying by the strip pitch 10 3 BPM16 38 Mechanical Assembly 10 3 1 lonization chamber electrodes The heart of the BPM16 38 is the dual ionization chamber electrode stack This is manufactured from special thin 4 PCB material using standard PCB manufacturing techniques which give extremely high geometric accuracy Cross hairs on the back sides of the cathodes are centred on the electrode strip patterns allowing external optical alignment Figure 17 Ionization chamber electrode assembly The anode PCB in the middle is copper clad on both sides to form the anode for both halves of the chamber Note that the strips on the cathodes are orthogonal to the sensing direction vertical strips sense in the horizontal axis for example The electrode assembly is mounted on a hollow bore spindle that provides a route for the signal ribbon cables HV bias coaxial cable and flow gas tube BPM16 38 User Manual BPM16 38 UM 131023 Page 31 of 48 PSI System Controls and Diagnostics Figure 18 Electrode assembly mounted on spindle 10 3 2 Gas pocket A gas and vacuum tight cap fits to the end of the spindle s
25. ly any offsets Mounting face Figure 3 BPM mounting face BPM16 38 User Manual BPM16 38 UM 131023 Page 15 of 48 PSI System Controls and Diagnostics 9 2 1 Coordinate conventions In the conventional beamline optics convention z 1s always directed along the beam forward direction thus tangent to beam trajectory when in a dipole field the horizontal X axis 15 defined as orthogonal to z and outwards along the radius of curvature of local dipole magnets and vertical Y axis being the orthogonal direction to Z and X and thus the non dispersion direction of dipole magnets However your facility may adopt a different convention check carefully to ensure you know how the BPM orientation you use relates to your coordinate system Bending by dipole magnet Figure 4 Ion optics standard coordinate convention Transport The BPM16 38 has a natural internal XY coordinate system arising from the way the cathode strips are numbered and this in turn 18 based on the assumption that an 13200 electrometer 1s used to read out the device using pin to pin cabling with channels 1 16 used for the vertical sensing and 17 32 for the horizontal Figure 5 shows this internal coordinate system BPM16 38 User Manual BPM16 38 UM 131023 Page 16 of 48 PSI System Controls and Diagnostics X Figure 5 BPM16 38 internal coordinate system 9 2 2 Beam direction The BPM can be inserted into the beamline facing in either di
26. ment of the vacuum bellows We therefore recommend that the BPM 15 returned to Pyramid for bellows replacement and refurbishment Full details of the procedure will be supplied on request to users who have received appropriate training 12 3 Microswitch adjustment The microswitches should close when the actuator moves to within 2 4 mm of the hard end stop You may need to adjust this if the switches are replaced or if the setup 1s lost due to other work of accident The BPM should not be under vacuum so that the motion can be made manually 12 3 4 Procedure 1 Move the BPM by hand to the fully retracted and fully extended positions Ensure the microswitch actuation block contacts the switch rollers as shown Figure 25 Microswitch adjustment step A Upper switch right and lower switch left 2 Half tighten the retaining screws and move between the two positions to confirm that both switches at each end close between 4 and 2 mm of the hard stop Adjust the positions as need to achieve this Use a DVM to measure switch continuity 3 When correct and consistent tighten the screws and do a final check 12 4 Spare parts Solenoid drive cable Pyramid Technical Cons Microswitch Signal and bias PCB Actuator control PCB BPM16 38 User Manual BPM16 38 UM 131023 Page 41 of 48 PSI System Controls and Diagnostics Anode cable assy Technical Cons BPM16 38 User Manual BPM16 38 UM 13102
27. mline and is leak tested in the final stage of manufacture and test It is not fully UHV compatible because it includes elastomer seals and thus cannot be baked to high temperatures Moderate heating of the metal body to 70C maximum is acceptable to accelerate outgassing The BPM may also be operated in atmosphere The operating environment should be clean and free of vibration Users should be familiar with vacuum technology and low current measurement 7 2 Key Features e ow insertion length and choice of vacuum connectors e Small gap ionization chamber with 16 by 16 sensing strips 38 mm by 38 mm sensitive area e Operation with atmospheric air or flow through gas e Bias voltage up to kV High vacuum compatible Robust low maintenance IC housing with bonded thin stainless steel windows e Integrated pneumatic actuation with dual limit switch end point sensing e Precision guides for in beam location e 100000 cycle nominal bellows life Compatible with the 13200 electrometer BPM16 38 User Manual BPM16 38 UM 131023 Page 10 of 48 PSI System Controls and Diagnostics 8 Specification Beam compatibility Protons deuterons helium ions carbon ions 30 MeV nucleon to 500 500 MeV nucleon 10 pA cm 2 to 20 nA cm 2 Sensor Parallel plate dual ionization chamber with multistrip cathodes 500 V to 2000 V Sensitive area 38 mm by 38 mm Vacuum pipe internal diameter will define sensitive area 6mm anode c
28. nd the BPM can be used to give a reasonable indication of beam current The approximate gain curve for the BPM16 38 with 6 mm electrode spacing as a function of beam energy for protons in air at standard ambient temperature and pressure is as shown in figure 10 below A value of 75 was measured for the BPM16 38 for 228 MeV protons with atmospheric air filling CAUTION If the BPM16 38 1s used for critical dosimetry applications then you must use accurate gain values referenced to traceable standards and regularly validated If the BPM is only being used to measure the position and shape of the beam then we don t need to know the gain accurately only that it is consistent across the chamber BPM16 38 User Manual BPM16 38 UM 131023 Page 25 of 48 PSI System Controls and Diagnostics 100 150 200 Proton energy MeV Gap 6 mm 150 200 Proton energy MeV Gap 6 mm Figure 11 Approximate gain curve for BPM16 36 protons in air at SATP BPM16 38 User Manual BPM16 38 UM 131023 Page 26 of 48 PSI System Controls and Diagnostics Since the gain at any beam energy 18 a function of the gas density in the electrode gaps it has to be corrected for variation in pressure and temperature relative to the gain at some reference pressure and temperature where it is known For example if you know the gain at standard atmospheric temperature and pressure SATP Temperature sArp 298 15 K Pressure 1
29. ndling and display must manage this coordinate transformation Rotation of the BPM by 90 degrees exchanges X and Y Rotation by 180 degrees swaps the directions of X and Y However a sensor mounted at an arbitrary angle mixes X and Y in the data which complicates interpretation and 15 therefore not recommended BPM16 38 User Manual BPM16 38 UM 131023 Page 18 of 48 PSI System Controls and Diagnostics 9 3 Cabling and services 9 3 1 Connections The following cable connections are required Actuator control and limit Dsub 9 way male Static lower body switch readback Redundant limit switch Weidmuller 3 81mm 4 way Static lower body readback optional terminal header male The following service connections are required Connector on the BPM16 38 Location on the BPM16 38 Fill gas in optional Threaded hole for 1 8 NPT Moving upper body fitting Fill gas out optional Threaded hole for 1 8 NPT Moving upper body fitting Figure 7 shows a schematic installation using the Pyramid 13200 electrometer for readout The 3200 is well suited as it provides HV bias and actuator control as well as ionization chamber readout BPM16 38 User Manual BPM16 38 UM 131023 Page 19 of 48 PSI System Controls and Diagnostics Pneumatic Flow gas in out pressure optional NON T7 Actuator control and readback Redundant limit switch output optional lt 2 4 A Si t gt m
30. nts Inc If you need to return a unit contact Pyramid Technical Consultants at support ptcusa com stating model serial number nature of fault CAUTION Radiation The unit cannot be shipped until it 1s certified to be below legal limits for radiation and that it 1s clear of any chemical contamination An RMA will be issued including details of which service center to return the unit to We recommend that you retain the original shipping carton to use for returns BPM16 38 User Manual BPM16 38 UM 131023 Page 45 of 48 PSI System Controls and Diagnostics 15 Support Manual and other documentation updates are available for download from the Pyramid Technical Consultants website at www ptcusa com Technical support is available by email from support ptcusa com Please provide the model number and serial number of your unit plus relevant details of your application BPM16 38 User Manual BPM16 38 UM 131023 Page 46 of 48 PSI System Controls and Diagnostics 16 Disposal We hope that the BPM16 38 gives you long and reliable service The BPM16 38 is manufactured to be compliance with the European Union RoHS Directive 2002 95 EC and as such should not present any health hazard once any activation has decayed CAUTION Radiation The BPM must not be released from a radiation controlled area until it has been surveyed and declared safe by a qualified Radiation Supervisor When your BPM16 38 has reached the en
31. on Maintain mechanism readout reaching end of travel has actuator reached as necessary and engaging with the hard stops alignment pins BPM is installed in Visual inspection Ensure calibration BPM16 38 User Manual BPM16 38 UM 131023 Page 43 of 48 PSI System Controls and Diagnostics orientation that check calibration values are correct invalidates calibration values being used values X and Y axis cables Check cable Ensure cables are swapped connected and secure Small or no signal bias not reaching Check HV supply Correct as necessary the BPM Check cable If no external cause of integrity missing HV remove BPM and check internal connection Unstable signal HV arcing due to high Reduce HV and see Improve air humidity if instability reduces conditioning Improve air Consider using flow conditioning gas Triboelectric noise Check signal again Use low noise cables when no vibration or Do not use data from movement immediately after the actuator is moved Leak check Aggravated by Repair as necessary actuator movement Leak check Leak check feed Replace gas pocket as helium into gas necessary pocket BPM16 38 User Manual BPM16 38 UM 131023 Page 44 of 48 PSI System Controls and Diagnostics 14 Returns procedure Damaged or faulty units cannot be returned unless a Returns Material Authorization RMA number has been issued by Pyramid Technical Consulta
32. osition Px Py expressed in strips then the position in physical units in the BPM coordinate system figure 5 1s given by Xs Px 24 5 5 Ys 8 5 5 To translate to the beamline coordinate system we must allow for any rotations of the BPM relative to the beamline coordinate system due to the way it is mounted and also for any residual offsets between the BPM sensor coordinate system and the beamline coordinate system The residual offsets between the sensor and the body of the BPM are determined during final factory test and are given in the test results The offsets are given in the BPM coordinate system in microns Alignment Check Measured Value Results Nominal channel value 8 5 24 48 Nominal channel value 24 5 dX lt 250microns 11421 PASS dv lt 250microns PASS Figure 13 Test result extract showing residual offsets of BPM sensor BPM16 38 User Manual BPM16 38 UM 131023 Page 28 of 48 PSI System Controls and Diagnostics Offsets of the BPM body relative to its ideal position in the beamline coordinate system will be determined during beamline survey The following example with grossly exaggerated offsets shows how a measured X position in sensor coordinates 15 translated to the beamline coordinate system We ll take the more complicated case where the beamline X axis direction 15 opposite to the BPM X axis direction Firstly the raw centroid Xs is found in the sensor coordinate system f
33. pressure has been removed 12 1 Pneumatic cylinder lubrication The cylinder should be lubricated with several drops of 10 weight engine oil every 500 hours of continuous operation At 4 seconds typical per in and out movement this corresponds to 450 000 cycles The procedure can be carried out with the BPM on the beamline 12 1 1 Procedure 1 Remove pneumatic pressure and make safe using the working procedures for your site 2 Disconnect the gas feed to the top of the cylinder BPM16 38 User Manual BPM16 38 UM 131023 Page 39 of 48 PSI System Controls and Diagnostics Disconnect pipe at push fit connector Figure 23 Cylinder lubrication step A 3 Unscrew the pressure reducing valve taking care not to change the setting 4 Drop lubricant into the cylinder bore Insert several drops of 10 weight oil Figure 24 Cylinder lubrication step 5 Reconnect the valve and pipe Restore the pneumatic pressure and cycle the actuator several times to confirm correct operation 12 2 Vacuum bellows replacement The vacuum bellows are rated for 100 000 cycles of operation You may wish to replace them as a preventative measure at or around this stage The BPM must be removed from the beamline and partially disassembled to replace the bellows BPM16 38 User Manual BPM16 38 UM 131023 Page 40 of 48 PSI System Controls and Diagnostics 12 2 4 Procedure The assembly requires precision alignment following replace
34. rection The choice may be constrained by physical interferences with other beamline components The sensor chamber is symmetric the only difference being which sensing axis the beam sees first as it passes through and whether the positive X direction for conventional beam optics coordinates has increasing or decreasing strip numbering Referring to figure 5 you can see that the internal coordinate system has the same sense as the conventional beamline optics system if the BPM is mounted with the pneumatic solenoid upstream If you mount in the other direction with the signal connectors upstream you must remember to make the necessary inversion when converting from BPM coordinates to conventional beamline coordinates As an example figure 6 shows how the BPM strips are arranged relative to the conventional beamline coordinate system if the beam enters the BPM faces shown in figure 5 BPM16 38 User Manual BPM16 38 UM 131023 Page 17 of 48 PSI System Controls and Diagnostics H sense 7 Ch32 Ch17 ch 1 Fa V sense EU Ch H sense Beamline Beamline coordinates coordinates Figure 6 BPM strip numbering relative to conventional beamline coordinates for beam entering via signal connector face left and via pneumatic connection face right With high energy beams the order in which the beam passes the vertical and horizontal halves of th
35. rom the cathode strip signals using a suitable centroid calculation Figure 14 Beam position in BPM sensor coordinates blue Next we recognize that the beam position relative to BPM body must be adjusted by the residual offset AXo measured in the factory This measurement tells us where the body is relative to the sensor coordinate system It is simplest to express this as the displacement of the sensor centre relative to the body which is the negation of the value dX given in the test data and in the sensor coordinate system BPM16 38 User Manual BPM16 38 UM 131023 Page 29 of 48 PSI System Controls and Diagnostics Figure 15 Displacement of BPM body coordinates red from BPM sensor coordinates blue Finally we change to beamline coordinates In this example this involves a change in the X axis direction and a further measured residual offset AX of the BPM body relative to the beamline stated 1n the beamline coordinate system 17 32 Figure 16 Change to beamline coordinates green Thus the beam position in beamline coordinates 1s Xp AX 16 38 User Manual BPM16 38 UM 131023 Page 30 of 48 PSI System Controls and Diagnostics where A 1 if the sensor X axis is in the same direction as the beamline axis and A 1 if it is in the opposed direction An alternative approach better suited to a final installation 15 to assign absolute positions to the strips in beamline coordinates with all sca
36. ssembly mounted on spindle eseeecsssssseeccocsssscceccosssscceoccsssssececcossssececossssssececossssseesossssssee 32 Figure 19 Gas pocket and foil 32 Figure 20 Vacuum housing with sensor extended in beam position engaged on alignment pins 33 Figure 21 Vacuum housing with sensor retracted out of beam position 33 Figure 22 Complete BPM assembly with sensor extended left and retracted right 34 Figure 25 Cylinder lubrication Step A eese tenete toro eor ein SR ge pone eui Fev C erue Cove 40 Figure 24 Cylinder lubrication step via chay eu Pen Te 40 Figure 25 Microswitch adjustment step A Upper switch right and lower switch left 41 BPM16 38 User Manual BPM16 38 UM 131023 Page 4 of 48 PSI System Controls and Diagnostics 3 Safety Information This unit 1s designed for compliance with harmonized electrical safety standard EN61010 1 2000 It must be used in accordance with its specifications and operating instructions Operators of the unit are expected to be qualified personnel who are aware of electrical safety issues The customer s Responsible Body as defined in the standard must ensure that operators are provided with the appropriate equipment and training The unit is designed to make measurem
37. t 3200 XP10 32 channel electrometer with 1 kV bias supply and actuator control I3200 XP20 32 channel electrometer with 2 kV bias supply and actuator control 6 2 Signal cables and cable accessories CAB D25M 5 D25F Cable multiway low noise DSub 25 pin male to DSub 25 way female 5 m CAB D25M 10 D25F Cable multiway low noise DSub 25 pin male to DSub 25 way female 10 m CAB SHV 5 SHV Cable coaxial HV SHV to SHV 5 m CAB SHV 10 SHV Cable coaxial HV SHV to SHV 10 m CAB D9M 5 D9F Cable multiway DSub 9 pin male to DSub 9 way female 5 m CAB D9M 10 D9F Cable multiway DSub 9 pin male to DSub 9 way female 10 m BPM16 38 User Manual BPM16 38 UM 131023 Page 9 of 48 PSI System Controls and Diagnostics 7 Intended Use and Key Features 7 1 Intended Use The BPM16 38 is intended to provide position and shape readout of high energy beams nominally proton beams in the energy range 30 to 350 MeV It will form a part of a complete beam diagnostics suite in a particle accelerator system The BPM performs a semi destructive measurement of the beam Although the beam passes through the device the amount of scattering it receives is generally too great for the beam downstream to be used for other purposes The BPM16 38 therefore includes a pneumatic actuator system to move the sensor element completely out of the beam path once the measurement has been made The BPM16 38 is intended to be incorporated into a high vacuum bea
38. travel In the extended position the travel limit is set by an adjustable hard stop pre set in manufacture which defines the position accuracy in the Y axis Figure 22 Complete BPM assembly with sensor extended left and retracted right BPM16 38 User Manual BPM16 38 UM 131023 Page 34 of 48 PSI System Controls and Diagnostics 11 Connectors 11 1 Electrical 11 1 1 Vertical sense signal output DSub 25 pin male 3 PP Pin 14 PIN e External view on connector solder side of mating plug View of cathode strips looking from the signal connectors side Cathode strips are on the front side of the cathode from this view 5 Stip7 19 8 Stip9 21 AGnd 9 Strip10 22 AGnd The connector 15 compatible with a pin to pin connection to an 13200 electrometer Strip 1 15 connected to channel 1 and so on up to strip 16 being connected to channel 16 BPM16 38 User Manual BPM16 38 UM 131023 Page 35 of 48 PSI System Controls and Diagnostics 11 1 2 Horizontal sense signal output DSub 25 pin male Pn 3 Pin 4 b 0 Pin 13 In External view on connector solder side of mating plug View of cathode strips looking from the signal connectors side Cathode strips are on the back side of the cathode from this view 6 8023 19 AGnd 8 Stip25 21 AGnd 2 3 j 4 5
Download Pdf Manuals
Related Search