C. A. Kletzing Department of Physics and Asttronomy The University of Iowa THE UNIVERSITY OF IOWA REPW 2007

Transcription

1 1 Waves in the Earth s Radiation Belt: The Electric and Magnetic Field Instrument Suite with Integrated Science (EMFISIS) on the Radiation Belt Storm Probes C. A. Kletzing Department of Physics and Asttronomy The University of Iowa craig-kletzing@uiowa.edu

2 2 RBSP Status Currently in Phase A doing detailed study of the mission, instruments, and satellite. Mission Design Review in early October Begin Phase B, the detailed design phase, in February, Hardware build (Phase C/D) begins in February, 2009 Launch is April, 2012 Orbits will be 1.1 R E x 5.5 R E and 1.1 R E x 5.8 R E Combines string of pearls (early) with slowly separating petals

3 3 RBSP Instrument Teams Science Investigations Dr. Harlan Spence, PI Boston University Dr. Craig Kletzing, PI University of Iowa Dr. John Wygant, PI University of Minnesota Dr. Louis Lanzerotti, PI New Jersey Institute of Technology Lt. Col. Clark Groves, PI National Reconnaissance Office ECT - Energetic Particle, Composition, and Thermal Plasma Suite: HOPE- Helium Oxygen Proton Electron top-hat analyzer and coincidence detector; MagEIS - Magnetic Electron Ion Spectrometer; REPT - Relativistic Electron ProtonTelescope EMFISIS - Electric and Magnetic Field Instrument Suite and Integrated Science Suite: MAG - Triaxial fluxgate Magnetometer; WAVES - Triaxial Search Coil and EFW - Electric Field and Waves Instrument: Spin Plane Double Probes; Axial Stacer Booms RBSPICE - Radiation Belt Storm Probes Ion Composition Experiment: PSBR - Proton Spectrometer Belt Research: RPS: Relativistic Proton Spectrometer

4 4 RBSP Satellite Configuration ECT REPT EFW Spin Plane Wire Boom (4x) EMFISIS MAG Boom RPS ECT MagEIS (Medium) ECT MagEIS (High) EMFISIS Search Coil Boom ECT MagEIS (Low) RB-Spice ECT MagEIS (Medium) ECT HOPE EFW Axial Boom (fwd & aft)

5 5 EFW Booms B Sensor 12.0m[472.4in] A EFW Axial Boom EFW Wire Boom 2x 1.0m [39.37in] 2x 40 m & 2x 50 m 4x 3.0 m Detail B Pre-Amp Sensor Detail A Pre-Amp

6 6 Particle Capabilities electrons protons HOPE HOPE RBSPICE MagEIS RBSPICE MagEIS REPT REPT Particle Sensors PSBR/RPS ECT/REPT ECT/MagEIS RB-SPICE ECT/HOPE RPS He+ HOPE RBSPICE O+ heavy ions HOPE RBSPICE MagEIS 1eV 1keV 1MeV 1GeV

7 7 Fields Capabilities DC Magnetic EMFISIS FGM AC Magnetic DC Electric AC Electric EMFISIS SCM EFW Perp 2D EFW Par 1D EFW AC 3D EFW E-fld Spectra 2D EMFISIS Waves EMFISIS Waves Fields & Waves Sensors EMFISIS/MAG EMFISIS/Waves EFW Density EMFISIS Density EFW cold plasma density ~DC 10Hz 1kHz 1MHz

8 8 EMFISIS Team Leads University of Iowa: Dr. Craig Kletzing, EMFISIS PI Dr. William Kurth, Waves Lead Goddard Space Flight Center: Dr. Mario Acuña, MAG lead University of New Hampshire: Dr. Roy B. Torbert, CDPU Lead UC, Los Angles Los Alamos National Lab Dr. Richard Thorne Dr. Vania Jordanova

9 9 EMFISIS Components and Performance Triaxial Magnetometer (MAG): vector B, DC-30 Hz 3 sensors on rigid boom 3 ranges: ± 256 nt, ± 4,096 nt and ± 65,536 nt corresponding resolutions: ± nt, ± nt ± 2nT absolute accuracy of 5 nt accuracy Central Data Processing Unit (CDPU): Instrument control, spacecraft interface, on-board analysis, 500 Mbyte mass memory EMFISIS data rate: 53 kbits/s.

10 10 EMFISIS Components and Performance Waves Magnetic field: vector B. 3 sensors on rigid boom. 10 Hz-12 khz. sensitivity: 3x10-11 nt 2 Hz khz. Electric field: vector E, shares booms with double probe experiment. 10 Hz-12 khz (vector),\ khz (single channel) sensitivity: 3x10-17 V 2 m -2 Hz 1 khz,

11 11 Key EMFISIS Waves Measurements Spectral matrices for 10 Hz 12 khz at 6 second cadence (more often is desired and necessary for some objectives) Spectrum, wave normal, and polarization summaries, based on both onboard and ground processing at 6 second cadence (or more often) Electric field spectrum to 400 khz with 6- second cadence; electron density from f UHR and continuum radiation cutoff Simultaneous 6-channel waveforms

12 12 Key EMFISIS MAG Measurements Rapid delivery of 4 vectors/s in a variety of coordinate systems (GSE, GSM, S/C, etc.). Later delivery of 64 vectors/s standard rate for all operating modes. Real time magnetometer data for space weather, 1 vector minute

13 13 Radiation Belt Waves

14 14 EMIC Waves

15 15 Key Wave Regions Wave-particle interactions are involved in both acceleration and loss of radiation belt particles

16 16 EMIC Waves Driven by ring current ions Interact with relativistic electrons via electron cyclotron resonance for either L or R polarization: This interaction results in pitch angle scattering and loss to the atmosphere. Frequencies in bands below ωcifor H+, He+, and O+ Amplitudes of 1-10 nt.

17 17 EMIC Wave Location CRRES statistical study by Meredith et al., 2003 examined characteriaticsof over 800 EMIC events

18 18 Location for Scattering E < 2 MeVe- Organization by plasmapause location reveals a second region of waves effective at scattering electrons with E<2 MeV

19 19 Plasmaspheric Hiss Generation mechanism is not well understood. Frequency range is 0.1 < f < 2 khz. Amplitudes up to ~100 pt, average ~40 pt. Interact with relativistic electrons via electron cyclotron resonance. As for EMIC waves interaction results in pitch angle scattering and loss to the atmosphere. Can scatter electrons from ~50 kev up to ~1 MeV in energy.

20 20 Hiss MLT Distribution Magnetic latitude less than 15 degrees CRRES statistical study by Meredith et al., 2004 examined characteristics of hiss finding tow latitudinal bands.

21 21 Hiss MLT Distribution Magnetic latitudes of 15 to 30 degrees Including a three hour time lag for the AE value used produced better organization of the data.

22 22 Hiss MLT Distribution Dayside distribution The two distinct regions seen in the MLT data are clearly seen.

23 23 Magnetosonic Equatorial Noise Intense, very linearly polarized, planar, and propagating almost exactly perpendicular to B. Frequency range is a few Hz up to f LH (<300 Hz) Amplitudes of nt 2 /Hz. Generated by proton ring distributions. Acceleration of electrons to relativistic energies via electron Landau resonance rather than the Doppler shifted electron cyclotron resonance. Horne et al., [2007] show that bounce-averaged energy and pitch angle diffusion are quite significant. Can give acceleration comparable to chorus.

24 24 Equatorial Noise Signature Santolik, 2004 analyzed 781 intvervalsof Cluster data

25 25 Equatorial Noise Location Santolik, et al., 2004 showed that intense linearly polarized events are observed exclusively at the equator

26 26 Equatorial Noise Power Santolik, et al., 2004 showed that linearly polarized waves form a significantly higher fraction of the most intense events.

27 27 Whistler Mode Chorus Generation mechanism is only generally understood. Two frequency ranges. Lower band is 0.1 fce 0.5 fce, upper band is 0.5 f ce 0.8 f ce Amplitudes up to 10-2 nt 2 /Hz, average during active times of ~10-3 nt 2 /Hz. Interact with electrons via electron cyclotron resonance to both scatter and accelerate electrons. Scattering is of lower energy electrons few kev to 100 kev. Acceleration of seed in electrons with 100 s of kevenergy up to MeVenergies is possible.

28 28 Chorus MLT Distribution Magnetic latitude less than 15 degrees CRRES statistical study by Meredith et al., 2003 examined characteriatics of chorus in two latitudinal ranges.

29 29 Hiss MLT Distribution Magnetic latitudes of 15 to 30 degrees At higher latitude, the most intense chorus shifts towards the dayside.

30 30 Chorus Latitude Distribution Low latitude chorus occurs predominantly in the night to dawn regions while higher latitude chorus is clealrya dayside phenomena.

31 31 Chorus Properties from Cluster The Cluster spacecraft observe the same chorus elements on multiple spacecraft. Each spacecraft has a unique temporal and frequency signature. Cross-correlation between spacecraft separates source temporal variation from propagation effects. Wave ray tracing allows us to investigate the source location. Source is identified as the region where all spacecraft signatures can be recreated. This then yields wave normal emission distribution.

32 32 Elements from Different Spacecraft From Brenneman, et al., 2007 (JGR)

33 33 Equatorial Noise Signature Santolik, 2004 analyzed 781 intvervalsof Cluster data

34 34 Ray Tracing A Common Source Rays at three frequencies from a source region identified as the X emitted toward the three spacecraft. The axes are in R E in the magnetic meridion plane. The two extreme rays at θ k = 62 (leftmost) and θ k = 62 (rightmost) are near the resonance cone. The two intermediate rays at θ k = 5 (middle left) and θ k = 55 (middle right) represent the wave normal span at the source needed to illuminate all three spacecraft.

35 35 Identifying the Source Region A common intersection is found for this case, but not all cases

36 36 Source Wave Normal Angles Wave normal mappoing of the source for ~4300 Hz.

37 37 Wave Normal Distribution

38 38 Wave Normal Distribution

39 39 Conclusions Many aspects of location and amplitude are known, but details are missing. More information on activity level correlation with location and amplitude will improve models. Generation mechanisms have many gaps. Detailed calculations need detail of wavenormal distributions these are now mostly assumed. Ray tracing of chorus provides one way of getting these distributions.

40 40 That s all folks!