The Thermal Ion Dynamics Experiment
and Plasma Source Instrument

*Deceased

ABSTRACT

The Thermal Ion Dynamics Experiment (TIDE) and the Plasma Source Instrument (PSI) have been developed in response to the requirements of the ISTP Program for three-dimensional (3D) plasma composition measurements capable of tracking the circulation of low-energy (0-500eV) plasma through the polar magnetosphere. This plasma is composed of penetrating magnetosheath and escaping ionospheric components. It is in part lost to the downstream solar wind and in part recirculated within the magnetosphere, participating in the formation of the diamagnetic hot plasma sheet and ring current plasma populations. Significant obstacles which have previously made this task impossible include the low density and energy of the outflowing ionospheric plasma plume and the positive spacecraft floating potentials which exclude the lowest-energy plasma from detection on ordinary spacecraft. Based on a unique combination of focusing electrostatic ion optics and time of flight detection and mass analysis, TIDE provides the sensitivity (seven apertures of 0.3 cm2 effective area each) and angular resolution (6û x 18û) required for this purpose. PSI produces a low energy plasma locally at the POLAR spacecraft that provides the ion current required to balance the photoelectron current, along with a low temperature electron population, regulating the spacecraft potential slightly positive relative to the space plasma. TIDE/PSI will: (a) measure the density and flow fields of the solar and terrestrial plasmas within the high polar cap and magnetospheric lobes; (b) quantify the extent to which ionospheric and solar ions are recirculated within the distant magnetotail neutral sheet or lost to the distant tail and solar wind; (c) investigate the mass-dependent degree energization of these plasmas by measuring their thermodynamic properties; (d) investigate the relative roles of ionosphere and solar wind as sources of plasma to the plasma sheet and ring current.

TABLE OF CONTENTS

LIST OF FIGURES
LIST OF TABLES

INTRODUCTION

SCIENCE OBJECTIVES
TIDE Specifications
PSI Specifications

TIDE INSTRUMENT DESCRIPTION
Mirror/RPA System
Collimator System
Rejection/Deflection System
TOF Detection System

PSI DESCRIPTION
Source System
PSI Gas Feed System

OPERATIONS
TIDE
PSI
Measurement Modes
Science Operations

SUMMARY

APPENDIX 1: Mirror Shape

APPENDIX 2: Electronics Description

ACKNOWLEDGEMENTS
REFERENCES