STK / SEET R
Contents
1. in scales and ranges of va lidity between the two graphs Electron Flux 10 10 1 Thu 300 Oct 2009 Ele Flux 0 650 bew m 2 sec 1 Mev 1 6 00 Time UTCG Ele Flux 0 950 Mey m 2 sec 1 Mew 1 4 00 1200 Ele Flux 1 600 Me m 2 se0 1 Mew 12. local point in space Lu and B B are computed internally from the user specified magnetic field model see the STK SEET Magnetic Field Tuto rial and the SEET user manual for more information Starting with STK SEET 9 2 3 two additional options for setting the magnetic field have been added to the SEET Radiation tab in the Satellite Basic Properties list which pro vide additional compatibility with the SPENVIS radiation environment computation technique These options are Set magnetic field epoch to Mode s reference epoch and Shift SAA using Mode s reference epoch Note that when these settings are selected the magnetic field model selections set in the Satellite Basic SEET Environment tab are ignored for the purposes of radiation environment computations See the SEET User Manual for further information Problem Statement For a given space vehicle configuration and orbit determine a low resolution data based dose depth curve for a long time base line orbit 6 months a high resolution model based dose depth curve for a long time base line orbit 6 months using flux integration a min max flux comparison on an intermediate time base line orbit single day Getting Started The primary decisions to make when developing a Radiation Environment scenario using STK involve determining which models to use and balancing accuracy or resolution of results versus computational speed e Decide which magnetic field model s
3. STK SEET RADIATION ENVIRONMENT TUTORIAL Contents INTRODUC TOM scence ea na ae ee a Ra Ga ce ne as PROBEER TAP MENT oriire occa casuaresorcausncecon et accel ca sees sos eeuetcoenanas ecneeceentae GE TRIN Gs STARTER es ne SOLUTION APPROACH ccnctuccsno1tesausuan ives oh causewau saretarosnecoectectsaceesansiewwsacrunsonsetasdtdanacenson ces Diece eee CMOS be D O A E E E E A E T Configure the Magnetic Field model for use with the Radiation Environment models Configure the Radiation Environment for a long time base dose depth analysis Configure the Radiation Environment for a high resolution dose depth analysis Configure the Radiation Environment for a min max flux comparison y Licenses Needed This tutorial requires that you be licensed for the STK Space Environmental Effects Tool SEET y Introduction The Radiation Environment component provides a suite of models for computing ener getic particle fluxes and fluences in near Earth space as well as ionizing dose rates and integrated doses behind user specified shielding thicknesses dose depth curves The flux models provided include the Air Force Research Laboratory AFRL CRRES models as well as the standard NASA AE8 AP8 models for both protons and electrons For dose quantities the data based APEXRAD and CRRESRAD models are provided which give total dose only for a limited set of shielding thicknesses as well as the stand
4. ard SHIEL DOSE 2 model which is highly configurable in terms of for example shielding thick ness and detector type and can provide the dosing due to protons electrons and brems strahlung separately Starting with STK SEET 9 2 3 computation with SHEILDOSE 2 has been sped up significantly by allowing the user to select a Dose Integration Step and Dose Report Step With these parameters fluxes are accumulated at the time resolution specified by the Dose Integration Step for a period corresponding to the Dose Report Step and then passed to SHIELDOSE 2 for dose computation Speed ups are on the order of Dose Report Step over orbit time step e g 1440 min 1 min 1440 for an integration interval of 1 day and orbit time step of 1 minute assuming Dose Integration Step orbit time step which is a reasonable choice Note to obtain the previous behav ior of the model simply set both the Dose Integration Step and Dose Report Step equal to the scenario time step Since the models for this component are essentially climatological databases obtained by binning satellite data in a magnetic coordinate space specifically Lu and B Bo a partic ular magnetic field model must be specified in order to access the data Here Lu 1s the MclIlwain L parameter a mathematical way of indexing an energetic particle s drift shell and B Bo is the ratio of the local magnetic field to the minimum magnetic field along the field line passing through the
5. ation Include Neutrons in Nuclear Attenuation The Radiation Only mode uses APEXRAD and CRRESRAD only and cannot compute radiation flux Set magnetic field epoch to Modes reference epoch Shift SAA using Mode s reference epoch Ap Flux Source File SpaceWeather v1 2 b Static Value 10 Source Static Value z Hep EE 7 To compute and view the dose depth report for this model bring up the Report and Graph Manger by selecting Analysis Report amp Graph Manager from the main menu Make sure Object Type Satellite 1s selected In the Styles pane ex pand the Installed Styles folder and scroll down to the SEET Radiation Dose Depth report style and double click it to launch the report Note that the report may not generate instantly It should look like the following Satellite Satellitel Shielding thickness Mils Combined dose rads 8 250e 001 8 165e 003 2 325e 002 6 802e 002 4 575e 002 3 141e 002 The units of the shielding thickness can be changed by right clicking on Mils in the report to expose an option menu Go to Shielding thickness Units to reveal the units panel Uncheck Use Defaults and set the New Unit Value to Millime ters mm Click OK Satellite Satellitel Shielding thickness mm Combined dose rads 2 095e 000 6 165e 003 5 905e 000 6 8024 002 1 162e 001 3 141e 002 Configure the Radiation Environment for a high resolution dose depth ana
6. e Report Step 24hr T Use Nuclear Attenuation Include Neutrons in Nuclear Attenuation W Set magnetic field epoch to Mode s reference epoch V Shift SAA using Mode s reference epoch Ap Aux Source File Space Weather v 1 2 tet Ca mm FE mm FE mm 15 mm 30 Graphics Pass Static Value 10 Orbit System es Source Static Value Attitude Sphere 12 Return to the Report amp Graph Manager configuration page Next from the list of Installed Styles right click on the SEET Radiation Dose Depth report and se lect Properties Click on Section 1 in the Report Contents box and click Re move Go to the data provider list on the left and expand the SEET Radiation Dose Depth object Add Shielding Thickness Electron Dose Electron Brehsstrahlung Dose Proton Dose and Combined Dose to the Report Contents list using the arrow button a 13 Highlight Shielding Thickness in the Report Contents box and then click the Units button Clear the Use Defaults checkbox and then click on a New Unit Value of Millimeters mm and then click OK Click Apply in the Reports amp Graphs window A warning pop up will be displayed asking to save this style under My Styles click OK Click OK on the Properties page to close it A SEET Ra diation Dose Depth report icon should now be high lighted under the My Styles folder Double click that icon or click the Generate b
7. ls cover the broadest spatial and ener gy ranges while the CRRES models are based on more recent data 1990s When 2 used in conjunction with large Dose Report Step sizes these models can also pro vide computationally efficient high depth resolution total dose depth curves Solution Approach Build a scenario that will cover the desired time period for the satellite orbit of interest Add a ground station of interest Set the relevant model parameters to achieve the desired balance between accuracy and computational speed Configure STK properties as needed to obtain the desired display Create the Scenario l Create a new scenario by using the New Scenario Wizard by selecting New from the File menu or by clicking the corresponding toolbar button amp Fill in the scenario name and description For the analysis period enter 1 Oct 2009 00 00 00 000 UTCG tol5 Oct 2009 00 00 00 000 UTCG Click OK and save the new scenario Next add a satellite to the scenario We will use a nominal eccentric orbit that co vers a large portion of the inner belt and a smaller portion of the outer belt which will exercise the Radiation Environment models in the desired manner Select menu nsert New Under Scenario Objects highlight Satellite Un der Select a Method choose Orbit Wizard In the Orbit Wizard window for Type select Orbit Designer then fill in the following values Semimajor A
8. lysis 9 10 11 Now we will configure the Radiation Environment for a high resolution 1 e many depths dose depth analysis and generate the corresponding report On the satellite s Properties page under Basic select SEET Radiation In the Model pane for Computational Mode select CRRES leave the Detector Type as Silicon and set the Detector Geometry to Spherical On the same page click the Remove All button in the Shielding Thicknesses box Click Add and enter 1 mm in the text box that appears then hit the Return or Enter key Repeat this for the following set of shielding thicknesses 2 mm 3 mm 4 mm 6 mm 8 mm 10 mm 15 mm Check the Set magnetic field epoch and Shift SAA boxes to override the environment magnetic field configuration for greater SPENVIS compatibility Leave Dose Integration Step at 60 sec and set Dose Report Step to 24 hours Click Apply Basic Orbit Attitude Pass Break Mass Eclipse Bodies Reference Ground Ellipses SEET Environm SEET Thermal SEET Particle Fl SEET Radiation Description 2D Graphics Attributes Time Events Pass Contours Range Lighting Swath Ground Ellipses SEET Environrm Satellitel Basic SEET Radiation Computational Mode CRRES Fr Dose Channel Total Decor Type Detector Geometry Spherical Y Dose Integration Step 60 sec Dos
9. se dose depth analysis Next we will configure the Radiation Environment for a long time base line dose depth analysis and generate the corresponding report Since these generally take very long to compute we will use the data based models On the Satellite Proper ties page under Basic select SEET Radiation In the Model box verify that Computational Mode is set to Radiation Only and Dose Channel is set to Total Set both the Dose Integration Step and the Dose Report Step to 60 sec and un check the Set magnetic field epoch box Leave all other options at their default values including the Shielding Thicknesses listed at the right Note that in Radiation Only CRRESRAD and APEXRAD Computational Modes only the prescribed sets of shielding thicknesses may be used Click Apply 6 Satellitel Basic SEET Radiation Basic Orbit Attitude Pass Break Mass Eclipse Bodies Reference Ground Ellipses SEET Environment SEET Thermal SEET Particle Flux SEET Radiation Description 2D Graphics Attributes Time Events Pass Contours Range Lighting Swath Ground Ellipses SEET Environment 3D Graphics Pass Orbit System Attitude Sphere Vector Phones ans ite a Ty W Computational Mode Radiation Only Dose Channel Total 4 Detector Type Silic on Detector Geometry Semi nfinite slab Dose Integration Step 60sec t Use Nuclear Attenu
10. to use Low Earth Orbits LEO under about 1500 km altitude generally do not require the external field model Tilted dipole is a good choice when computational speed is a high priority IGRF main field with Olson Pfitzer gives the highest accuracy Fast IGRF is reasonably accu rate within 1 of IGRF and intermediate in speed Fast IGRF with Olson Pfitzer external is typically a good choice here in nearly all circumstances e Determine the optimal IGRF update rate This determines how frequently the IGRF model coefficients are recomputed The default of 1 day should be fine for most circumstances but increasing it to up to 30 days for very long orbits can im prove computational speed e Note that the field choice is pre determined and set automatically when the Set magnetic field epoch to Mode s reference epoch option in the Satellite Basic SEET Radiation tab is selected e Decide which Radiation Environment models to use APEXRAD CRRESRAD or Radiation only APEXRAD except where out of range of that model in which case CRRESRAD is used are fast data based models but with a limited range of shielding depths They should be used for computationally fast high resolution dose rate computation over long orbits However for access to the full range of SHIELDOSE 2 options selectable depths different detector types species resolved doses greater spatial range of validity either the CRRES or NASA models must be selected The NASA mode
11. utton Note that this report could take a couple minutes to generate depending on computer perfor mance Satellite Satellitel Shielding thickness mm Ker On F amp F WH FE 000e 000 000e 000 000e 000 000e 000 000e 000 000e 000 000e 001 500e 001 Electron dose rads N MH Hi EH Un NH 721e 004 908e 003 014e 002 256e 002 454e 001 892e 000 841e 001 192e 006 Electron Bremsstrahlung dose rads KF MN WwW BB SF N 851e 001 273e 001 268e 000 988e 000 233e 000 582e 000 311e 000 860e 000 Proton dose rads 071e 003 520e 003 083e 003 645e 002 438e 002 755e 002 175e 002 554e 002 Combined dose rads Hi N ND BOBAN 131e 004 440e 003 592e 003 951e 002 615e 002 800e 002 201e 002 572e 002 Configure the Radiation Environment for a min max flux comparison 14 Return to the Report amp Graph Manager page Set the stop time to 1 Oct 2009 Electron Flux 12 00 00 000 UTCG In the Installed Styles folder double click on SEET Radia tion Electron Flux to create the graph 10 11 10 10 IN 10 107 a 1 Thu 3 00 6 00 9 00 12 00 Oct 2004 Time fUTCG a a es Ele Flux 0 650 Mev m 2 sec 1 Mev 1 Ele Flux 0 950 Mev m 2 sec4 Me 1 Ele Flux 1 600 Me m 2 sec1 Mev 1 15 Go to the Satellite Properties page Select Computation Mode NASA and click Apply Return to the Report amp Graph Manager page again and double click SEET Radiation Electron Flux Note the difference
12. x is 15000 km Eccentricity 0 4 Inclination 30 deg Argument of Perigee 50 deg RAAN 90 deg Then click OK Close the Insert STK Objects dialog box Right click the scenario object in the Object Browser and select Properties Un der Basic select Units then scroll down to RadiationShieldThickness and se lect Millimeters mm Returning to Basic select SEET Radiation In the NASA Electron and Proton Activity box change the dialog to Solar Max Click OR Configure the Magnetic Field model for use with the Radiation Envi ronment models 5 Right click on the satellite object in the Object Browser and select Properties In the properties panel tree under Basic select SEET Environment The upper dialog box contains the magnetic field parameters We will set these to the stand ard set for use with the Radiation Environment Set the Main Field dialog to Fast IGRF and the External Field to Olson Pfitzer Leave the IGRF update rate as it is and click Apply Satellitel Basic SEET Environment Basic Orbit Attitude Pass Break Mass Eclipse Bodies Reference Ground Ellipses SEET Environment SEET Thermal SEET Particle Flux SEET Radiation Magnetic Field Model Main Field Fast IGRF ka Bien Fel IGRF Update Rate 1 day South Atlantic Anomaly SAA Configure the Radiation Environment for a long time ba
Download Pdf Manuals
Related Search