AD-A251 245 PL-TR-92-2035 THE DEVELOPMENT OF STATIC AND DYNAMIC MODELS OF THE EARTH'S RADIATION BELT ENVIRONMENT THROUGH THE STUDY OF PLASMA WAVES, WAVE-PARTICLE INTERACTIONS AND PLASMA NUMBER DENSTTIES FROM IN SITU OBSERVATIONS IN THE EARTH'S MAGNETOSPHERE WITH THE CRRES SPACERAD INSTRUMENTS R. R. Anderson OTI ' D. A. Gurnett ELEFCTit Department of ' Physics and Astron~omy MAY20, 'i 4 The University of Iowa Iowa City, IA 52242-1479 .I ... AlIl January 1, 1992 " L.' D ,,C I..~b3e In Scientific Report No. 1 Approved for public release; distribution unlimited PHILLIPS LABORATORY AIR FORCE SYSTEMS COMMAND HANSCOM AIR FORCE BASE, MASSACHUSETTS 01731-500 92-13351 EHl|fll ' "This technical report has been reviewed and is approved for publication" MICHAEL VIOLET, LT, USAF iLEN Contract Manager Branch Chief WILLIAM SW R Deputy Di ector This document has been reviewed by the ESD Public Affairs Office (PA) and is releasable to the National Technical Information Service (NTIS). 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TITLE AND SLBITI I S FUNDING NUMBERS The Development of Static and Dynamic Models of the Earth's Radiation Belt Environment through the Study of Plasma Waves, Wave-particle Interactions and F 19628-90-K-0031 Plasma Number Densities from in situ Observations in the Earth's Magnetosphere with the CRRES SPACE RAD Instruments PE62101F PR7601 6. AUTHOR(s) TA22 R. R. Anderson WUI0 D. A. Gurnett 7. PERFORMING ORGANIZAIiON NAME(S) AND ADDRESS(E) B. PERFORMING ORGANIZA tION REPORT NUMuIR Department of Physics and Astronomy The University of Iowa Iowa City, IA 52242 9. SPONSORINGIMONITORING AGENCY NAME(S) AND ADDRESS(ES) 10 SPONSORING/MONITORING AGENCY REPORT NUMBER Phillips Laboratory PL-TR-92-2035 Hanscom AFB, MA 01731-5000 Contract Manager: LT. Michael Violet, USAF/PHP 11. SUPPLEMENTARY NOTES 12a. DISTRIBIJTIONIAVAILABILITY STATEMENT 12b DISTRIBUTION CODE Approved for public release; distribution unlimited 13. ABSTRACT (Maximum 200 words) This report describes the achievements of the first year of effort on data acquired by The University of Iowa/AFGL Plasma Wave Experiment (PWE) (AFGL 701-15 Passive Plasma Sounder and AFGL 701-13-2 Search Coil Magnetometer) which was a part of the SPACERAD complement of instruments on the Combined Release and Radiation Effects Satellite (CRRES). The primary purpose of the PWE is to study plasma waves, wave-particle interactions, and plasma number densities in the radiation belts of the Earth's magnetosphere as observed by the CRRES SPACERAD instruments in order to provide essential parameters for understanding both the long-scale and short-scale temporal and spatial variations of the individual particle species and waves and their inter-relationships. Computer programs to display and analyze the CRRES PWE data from both the real-time data collected at CSTC (The U.S. Air Force's Consolidated Space Test Center at Onizuka AFB in Sunnyvale, California) and the Agency Tapes have been developed and utilized to study the PWE data and to extract the electron number density throughout the CRRES orbit. Many significant new discoveries have been made including detailed observations of the fine structure in density variations and their association with enhanced low frequency electric field emissions, observations of deep cavities and ducts within the plasmasphere, and detection of multiple bands of emissions associated with multiple populations of energetic electrons. 14. SUBJECT TERMS 15. NUMBER OF PAGES Plasma Waves, Electron Number Density, Wave-Particle Interactions, 84 Radiation Belts 16 PRICCEO DE 17. SECURITY CLASSIFICATION 1Is SECURITY CLASSIFICATION IJ SE(UIRIIY CLASSIICAIION 20 LIMITATION (l7 ABSTRACT OF REPONI OfO TIS PAGE OF ABStRACT Unclassified Unclassified Unclassified SAR SIAN(lARD FORM 88 11,. 2t 8) Presc ribed by ANSI id 239 18 298.102 TABLE OF CONTENTS Page 1. INTRODUCTION .. ............... .......... 1 2. EXPERIMENT STATUS AND OPERATIONS .. ............... 10 3. PROGRESS AND CURRENT ACTIVITIES. ................ 23 3.1 Development of Algorithms to Derive Key Parameters Useful for Analyzing CRRES, Data. .............. 23 3.2 Development of Statistical and Event Studies. ........ 33 3.3 Initial Results and New Discoveries. ............ 47 4. FUTURE PLANS. ....... ................... 56 5. CONTRACT AND PERSONNEL ACKNOWLEDGMENTS .. ............ 58 APPENDIX 1: Abstracts of Papers Presented APPENDIX 2: The CRRES Plasma Wave Experiment A! !!85 Ofl For IITIS GRAi DTIc, TAB Q3 Unzn1 f~d DiAetV iJuSpiato iedo e0 iii 5. 1. INTRODUCTION This document constitutes the first annual technical report on the Air Force Contract F19628-90-K-0031 with The University of Iowa for the Development of Static and Dynamic Models of 'he Radiation Belt Environment through the Study of Plasma Waves, Wave-Particle Interactions, and Plasma Number Densities in the Radiation Belts of the Earth's Magnetosphere. The primary purpose of the investigation is to study plasma waves, wave-particle interactions, and plasma number densities in the radiation belts of the Earth's magnetosphere as observed by the Combined Release and Radiation Effects Satellite (CRRES) SPACERAD instruments in order to provide essential parameters for understanding both the long-scale temporal and spatial variations of the individual particle species and waves and their inter- relationships. The primary CRRES instrument involved in this investigation is The University of Iowa/Phillips Laboratory (formerly Geophysics Laboratory (GL) and Air Force Geophysics Laboratory (AFGL)) Plasma Wave Experiment which is comprised of the CRRES SPACERAD AFGL- 701-15 (Passive Plasma Sounder) and AFGL-701-13-2 (Search Coil Magnetometer) experiments. The measurement and study of the plasma wave environment in the radiation belts are essential to the SPACERAD mission because plasma waves play a major role in changing the energetic particle population through pitch angle scattering, ion and electron heating, and other wave-particle interaction processes which exchange energy and/or momentum between the waves and the particles. Evaluation of the plasma wave data allows the characterization of the plasma waves and the measurement of the electron number density. Characterization of the 1 plasma waves includes determining the spectral characteristics (intensity as a function of frequency), polarization (intensity as a function of angle between the antenna and the ambient magnetic field) and the degree to which the waves are electromagnetic or electrostatic by comparing the measurements from the search coil magnetometer and the long electric antennas. The characterization of the plasma waves is important for identifying the wave modes taking part in the wave- particle interaction processes and for evaluating the effect of the waves on the particles. The plasma wave data from CRRES allows a sheath-independent determination of the total electron number density throughout CRRES orbit. The electron number density is a necessary parameter for evaluating wave dispersion relations and determining the resonant energies in the various wave-particle interaction processes. Using the assumption of charge neutrality, the measurement of the total electron number density can also be used to determine the number density of low energy ions not detectable due to spacecraft sheath effects or detector characteristics. A comparison of the plasma wave measurements with the plasma and energetic particle measurements are used to study the various wave-particle interaction processes both on a statistical basis for long-term modelling studies and on a short-term event basis such as during magnetic storms. The CRRES Plasma Wave Experiment was designed to adequately measure the plasma wave environment in the Earth's radiation belts with emphasis on high frequency and time resolution, a large dynamic range, and sufficient frequency response to cover the majority of the characteristic frequencies of the plasma that are of interest and to determine the electron number density continuously over the range from 2 10-2 to 2 x 103 cm-3 using passive sounding techniques. The CRRES Plasma Wave Experiment provides measurements of electric fields from 5.6 Hz to 400 kHz and magnetic fields from 5.6 Hz to 10 kHz with a dynamic range of at least 100 dB. Electrostatic dN/N measurements from 5.6 Hz up to 400 kHz are also possible via signals from the Langmuir Probe Experiment. The 5.6 Hz to 400 kHz frequency range of the CRRES Plasma Wave Experiment covers most of the important characteristic frequencies expected to be encountered by CRRES in the region above about 2 RE (Earth radii). Below about 2 RE when the plasma frequency exceeds 400 kHz, the Langmuir Probe Experiment can provide the electron number density measurements. Electromagnetic plasma waves below 5.6 Hz are in the frequency range covered by the Fluxgate Magnetometer Experiment. Electric field fluctuations below 5.6 Hz can be measured by the Langmuir Probe Experiment. The Plasma Wave Experiment primary sensors consist of an extendable 100-meter tip-to-tip fine wire long electric dipole antenna (designated WADA for Wire Antenna Deployment Assembly) and a search coil magnetometer mounted on an Astromast boom 6 meters away from the spacecraft. The primary sensors for the Langmuir Probe Experiment, double spherical probes separated by about 100 meters (designated SWDA for Spherical-probe Wire Deployment Assembly) can also be used for either electric field measurements (when the Langmuir Probe Experiment is in the Voltage mode) or electrostatic dN/N measurements (when the Langmuir Probe Experiment is in the Current mode) by the Plasma Wave Experiment. The basic CRRES Plasma Wave Instrumentation includes two receivers: (1) a 128-channel Sweep Frequency Receiver (SFR) for high- 3 frequency-resolution spectrum measurements from 100 Hz to 400 kHz and (2) a 14-channel Spectrum Analyzer (SA) to provide high-time-resolution spectra from 5.6 Hz to 10 kHz. The dynamic range for both of the receivers is about 100 dB (a factor of 105 in amplitude) beginning at the respective receiver's noise level. The Sweep Frequency Receiver covers the frequency range from 100 Hz to 400 kHz in four bands with 32 logarithmically-spaced steps per band. The fractional step separation of the Sweep Frequency Receiver, df/f, is about 6.7% across the entire frequency range. Band 1 (100 Hz to 810 Hz) is sampled one step per second or 32 seconds per sweep. Band 2 (810 Hz to 6.4 kHz) is sampled two steps per second or 16 seconds per sweep. Band 3 (6.4 kHz to 51.7 kHz) and Band 4 (51.7 kHz to 400 kHz) are each sampled four steps per second or 8 seconds per sweep. The nominal bandwidths of the four bands are 7 Hz, 56 Hz, 448 Hz, and 3.6 kHz, respectively. The four bands each have a logarithmic compressor which measures the signal amplitude over about a 100 dB dynamic range beginning at the noise level of the receiver and produces a 0.0 to 5.10 Volt DC analog output proportional to the logarithm of the input amplitude. The Multichannel Spectrum Analyzer consists of 14 narrow-band filters logarithmically spaced in frequency (4 filters per decade in frequency) from 5.6 Hz to 10 kHz followed by 14 logarithmic compressors each having a dynamic range of about 110 dB. The nominal 3 dB sine wave bandwidth of each narrow-band filter is ±15% of the center frequency except for the two highest frequency channels (5.62 kHz and 10.0 kHz) whose bandwidths are ±7.5% of the center frequency. The 14 4 0.0 to 5.10 Volt DC analog outputs are sampled simultaneously 8 times per second to produce high time resolution spectra. The Spacecraft Telemetry Data System provides the clock and command lines for controlling the receivers- and the sampling and the analog to digital conversions of the receivers' 0.0 to 5.10 Volt DC analog outputs. The CRRES Plasma Wave Experiment has two high-level relay commands and one 16-bit serial command. The high-level relay commands turn the experiment power on and off. The serial command determines which sensor is connected to which receiver and whether or not the receivers are locked onto a single sensor or cycle through all of the sensors. When the SFR is commanded to the cycle mode (CYCLE1), its input is cycled E-B-E-LANG at a 32 second per sensor rate (E is the long electric dipole antenna; B is the search coil magnetometer; and LANG is the input from the Langmuir Probe Experiment). When the SA is commanded to the cycle mode (CYCLE2), its input is cycled B-E-B-LANG at a 4 second per sensor rate. The modes of the two receivers are independent of each other. A complete description of the CRRES Plasma Wave Experiment is included in Appendix 1 of this report. Many spacecraft have flown through the radiation belts over the past 32 years but none have been so ideally suited to study the radiation belt environment as the SPACERAD part of CRRES is. The extensive complement of plasma and particle instruments provide details of the particle distribution functions not generally available before. Between the CRRES Plasma Wave Experiment, the University of California, Berkeley (UCB)/AFGL 701-14 Electric Field/Cold Plasma Langmuir Probe experiment, and the AFGL/UCB 701-13 Fluxgate Magnetometer Experiment substantially more and higher-quality data are available on the 5