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

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

THEMIS/SRR ESA- 3 UCB, 06/08/2003 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 (<10sec required) ( , , , , ). ESA-2: The ESA shall measure differences in velocity and ion pressure between probes in the magnetotail plasma sheet ( ). ESA-3: The ESA shall measure, at one spin resolution, ion and electron distributions that are associated with the current disruption process ( ) 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) ESA Science Requirements

THEMIS/SRR ESA- 4 UCB, 06/08/2003 ESA-5: The ESA shall measure ions and electrons over an energy range of keV (ESA-1) ESA-6: The ESA energy sampling resolution, dE/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 keV/cm^2/s/Str/keV (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) ESA Performance Requirements Continued… (next slide)

THEMIS/SRR ESA- 5 UCB, 06/08/2003 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 6degrees (ESA-4) ESA-12: The ESA shall produce measurements of particle distributions over the entire 4pi 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). ESA Performance Requirements …Continued (from previous slide)

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

THEMIS/SRR ESA- 7 UCB, 06/08/2003 Ion ESA (16 anodes) Electron ESA (8 anodes required 16 anodes possible) 22.5 deg 5.6 deg deg { Requirement: 22.5 deg Common w/ IESA: deg (if resources permit, simplifies electronics) ESA Anode Implementation

THEMIS/SRR ESA- 8 UCB, 06/08/2003 Electronics design has direct heritage from FAST Three circuit modules plug together for efficient assembly and test MCP pulse amplifiers are Amptek A121 with programmable gain All discrete logic, counters, and HV DAC drivers are Actel FPGAs HV supplies are a mature design built at UCBSSL Electron & Ion Electrostatic Plasma Analyzers (ESA)

THEMIS/SRR ESA- 9 UCB, 06/08/2003 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 Electron & Ion Electrostatic Plasma Analyzers (ESA) Calibration Chamber