THEMIS Electrostatic Analyzer ESA instrument David W Curtis

THEMIS Electrostatic Analyzer (ESA) instrument David W. Curtis Space Sciences Laboratory University of California, Berkeley THEMIS/SRR ESA- 1 UCB, 06/08/2003

Electron & Ion Electrostatic Plasma Analyzers (ESA) • Direct Copy of FAST ESA design Changes from FAST: Solar Wind Ion Attenuator Ion Detector Anode Location THEMIS ESA Module MCP • 2 analyzers share common package (1/2 of a FAST module) • Modular for efficient testing, assembly, and repair • Entrance sealed and nitrogen purged FAST ESA Module Pulse Amplifiers Digital Interface & HV Sweep } HV Supplies THEMIS/SRR ESA- 2 UCB, 06/08/2003

ESA Science Requirements • ESA-1: The ESA shall obtain partial moments of the 3 -dimensional plasma electron and ion distributions with one spin period time resolution in the magnetotail plasma sheet (<10 sec required) (4. 1. 1. 3, 4. 1. 1. 6, 4. 1. 1. 7, 4. 1. 1. 9, 4. 1. 1. 10). • ESA-2: The ESA shall measure differences in velocity and ion pressure between probes in the magnetotail plasma sheet (4. 1. 1. 7). • ESA-3: The ESA shall measure, at one spin resolution, ion and electron distributions that are associated with the current disruption process (4. 1. 1. 11) • ESA-4: The ESA shall be capable of measuring ion moments and differences of those moments in the magnetosheath and solar wind (dayside science – secondary objective) THEMIS/SRR ESA- 3 UCB, 06/08/2003

ESA Performance Requirements • ESA-5: The ESA shall measure ions and electrons over an energy range of 0. 01 -30 ke. V (ESA-1) • ESA-6: The ESA energy sampling resolution, d. E/E, shall be better than 25% FWHM for ions and electrons (ESA-1, ESA-3) • ESA-7: The ESA shall be capable of measuring ion and electron energy flux of 10^4 to 10^9 ke. V/cm^2/s/Str/ke. V (baseline science; magnetotail plasma sheet fluxes) (ESA-1, ESA-2) • ESA-8: The ion ESA geometric factor shall be attenuated in the solar wind to avoid saturation (ESA-4) Continued… (next slide) THEMIS/SRR ESA- 4 UCB, 06/08/2003

ESA Performance Requirements …Continued (from previous slide) • ESA-9: The ESA shall supply partial energy moments at one spin time resolution (ESA-1, ESA-2, ESA-4). • ESA-10: The ESA shall have a 180 degree elevation field of view with a minimum angular resolution of 22. 5 degrees (ESA-1, ESA-4). • ESA-11: To resolve the solar wind, the ESA shall have a field of view with enhanced resolution of approximately 6 degrees (ESA-4) • ESA-12: The ESA shall produce measurements of particle distributions over the entire 4 pi steradian field of view in one spin period (ESA-1). • ESA-13: ESA calibration shall ensure <20% relative flux uncertainty (not including statistical uncertainty) over the ranges defined above (ESA-2, ESA-4). THEMIS/SRR ESA- 5 UCB, 06/08/2003

Backup slides THEMIS/SRR ESA- 6 UCB, 06/08/2003

ESA Anode Implementation Common w/ IESA: 11. 25 deg (if resources permit, simplifies t: electronics) n e 22. 5 deg em r i u eg q Re. 5 d 22 5. 6 deg THEMIS/SRR { 11. 25 deg Electron ESA (8 anodes required 16 anodes possible) Ion ESA (16 anodes) ESA- 7 UCB, 06/08/2003

Electron & Ion Electrostatic Plasma Analyzers (ESA) • • • Electronics design has direct heritage from FAST Three circuit modules plug together for efficient assembly and test MCP pulse amplifiers are Amptek A 121 with programmable gain All discrete logic, counters, and HV DAC drivers are Actel FPGAs HV supplies are a mature design built at UCBSSL THEMIS/SRR ESA- 8 UCB, 06/08/2003

Electron & Ion Electrostatic Plasma Analyzers (ESA) • Automated calibration • Cryogenic pumped vacuum chamber with computer controlled ion and electron guns and 3 -axis manipulators • All six ESA units (5 flight/ 1 spare) use identical calibration procedures adapted from FAST • Full environmental testing (Thermal / Vacuum, EMC, Vibration) 3 Axis Manipulator Calibration Chamber THEMIS/SRR ESA- 9 UCB, 06/08/2003