Development of Advanced Plasma Mass Spectrometry for Future Space Missions, 15-9362

Principal Investigators
David T. Young
Craig J. Pollack

Inclusive Dates: 11/01/02 - Current

Background - Earth is surrounded by a magnetosphere that interacts strongly with plasma flowing supersonically from the sun. Interactions between the magnetosphere and solar wind generate powerful electric currents dissipating ~10¹⁰ W. These are associated with the Earth's aurora as well as interruptions to commercial power grids. The process behind these phenomena is magnetic reconnection in which magnetic fields found in our sun are annihilated, accelerating plasma to high energies (similar processes on the sun generate 10²¹ W!). Despite its importance and the existence of reconnection in the Earth's magnetosphere, in situ measurements have thus far yielded little. Definitive studies require separation of spatial and temporal features on very short scales (10 km and 0.010 s) with high accuracy. No such measurements have been feasible up to now.

Approach - To gain a comprehensive understanding of reconnection, NASA is undertaking the Magnetospheric Multi-Scale mission (MMS), which consists of four identical spacecraft orbiting the Earth in tetrahedral formation while making simultaneous high-speed measurements in regions where reconnection is anticipated. Southwest Research Institute®, as leader of the SMART (Solving Magnetospheric Acceleration, Reconnection, and Turbulence) team, was recently selected by NASA to perform a 6-month concept study for the MMS scientific payload. In addition to leading SMART, SwRI is responsible for developing a key instrument, the Hot Plasma Composition Analyzer (HPCA). The HPCA is an ion mass spectrometer capable of viewing a 10° x 360° swath of the sky while obtaining mass- and energy-resolved spectra every 6 s. The HPCA will measure the density, velocity, and temperature of all ion species in the plasma with unprecedented accuracy while requiring only minimal mass and power.

Accomplishments - An early version of the HPCA electro-optical design executed under this IR contributed to selection of SMART for the NASA concept study. The HPCA concept design has since been developed into a prototype unit that will be tested during the NASA study. Among the most important developments to this point are dynamic control of particle detection rates, high rate time-of-flight measurement electronics, and high slew rate (~10⁶ V/s) low-current power supplies. The integrated prototype will be finished by the end of calendar year 2003 in time for testing before submittal of the NASA concept study in early 2004.

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