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U N C L A S S I F I E D Operated by the Los Alamos National Security, LLC for the DOE/NNSA Direct measurements of chorus wave effects on electrons in the.

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Presentation on theme: "U N C L A S S I F I E D Operated by the Los Alamos National Security, LLC for the DOE/NNSA Direct measurements of chorus wave effects on electrons in the."— Presentation transcript:

1 U N C L A S S I F I E D Operated by the Los Alamos National Security, LLC for the DOE/NNSA Direct measurements of chorus wave effects on electrons in the 5-40 KeV range from the Van Allen Probes Mission R. Friedel 1, Z. Hong 2, B. Larsen 1, G. Reeves 1, R. Skoug 1, C. Kletzing 3, M. Henderson 1 and Y. Chen 1 LANL 1, LASP 2,University of Iowa 3

2 U N C L A S S I F I E D Slide 2 Operated by the Los Alamos National Security, LLC for the DOE/NNSA AGU Chapman Conference, Jeju, South Korea, August 31 – September 5, 2104 Contents Motivation Pitch angle Statistics from HOPE and MagEIS – Pitch angle model – First results Two Spacecraft Event Selection – Matching Drift Paths – Filtering ephemeris information Event with waves at spacecraft at later MLT Event with NO waves Events summary Summary/Conclusion

3 U N C L A S S I F I E D Slide 3 Operated by the Los Alamos National Security, LLC for the DOE/NNSA AGU Chapman Conference, Jeju, South Korea, August 31 – September 5, 2104 Motivation The Van Allen Probe Mission with 2 spacecraft and exquisite particle and wave instrumentation is designed to explore the effects of Magnetospheric waves on the in-situ particle populations. We focus on the region of most active chorus wave activity, just outside the plasmapause, and on the energy range of particles most strongly affected by chorus waves (10's of keV, the top energy range of HOPE), and seek out changes in the pitch angle distribution (PAD) of the electrons that drift from one probe to the other– in either the presence or absence of chorus waves. Hypothesis: – We expect NO change in the PAD or flux levels for NO waves. – We expect a lowering of the flux levels and a flattening of the PAD (isotropization) in the presence of waves.

4 U N C L A S S I F I E D Slide 4 Operated by the Los Alamos National Security, LLC for the DOE/NNSA AGU Chapman Conference, Jeju, South Korea, August 31 – September 5, 2104 Pitch angle distribution (PAD) characterization / fitting (Chen et al., 2014) Use Legendre polynomials – where α is the pitch angle, j is the flux, P n is the Legendre polynomial, C n is the corresponding coefficient. – P 0, P 2, P 4, P 6 …: symmetric; P 1, P 3, P 5, ….: asymmetric Normalization – Directionally averaged flux Only keep c 2, c 4 and c 6 for statistics PAD Selection – Equatorial PAD – counts >50 – assume 90 O symmetry – keep good fits only

5 U N C L A S S I F I E D Slide 5 Operated by the Los Alamos National Security, LLC for the DOE/NNSA AGU Chapman Conference, Jeju, South Korea, August 31 – September 5, 2104 Pitch angle distribution (PAD) characterization / fitting (Chen et al., 2014) Butterfly PAD: negative c4 Normal PAD Butterfly PAD Flattop PAD

6 U N C L A S S I F I E D Slide 6 Operated by the Los Alamos National Security, LLC for the DOE/NNSA AGU Chapman Conference, Jeju, South Korea, August 31 – September 5, 2104 PAD comparison under different Kp (MagEIS E=35 keV) c4 c6 c2 Kp > 3+1+ < Kp ≤ 3+Kp ≤ 1+ Work done by Z. Hong, 2014 LANL SW Summer School

7 U N C L A S S I F I E D Slide 7 Operated by the Los Alamos National Security, LLC for the DOE/NNSA AGU Chapman Conference, Jeju, South Korea, August 31 – September 5, 2104 L=4.0 L=4.8L=5.5 PAD comparison under different Kp (MagEIS E=35 keV) – Sample PADs Inside Plasmasphere -> Outside Plasmasphere 90 O -> “Head and Shoulders” Work done by Z. Hong, 2014 LANL SW Summer School

8 U N C L A S S I F I E D Slide 8 Operated by the Los Alamos National Security, LLC for the DOE/NNSA AGU Chapman Conference, Jeju, South Korea, August 31 – September 5, 2104 PAD comparison under different Kp (HOPE E=5 keV) c4 c6 c2 Kp > 3+1+ < Kp ≤ 3+Kp ≤ 1+ Work done by Z. Hong, 2014 LANL SW Summer School

9 U N C L A S S I F I E D Slide 9 Operated by the Los Alamos National Security, LLC for the DOE/NNSA AGU Chapman Conference, Jeju, South Korea, August 31 – September 5, 2104 PAD comparison under different Kp (HOPE E=5 keV) – Sample PADs Inside Plasmasphere -> Outside Plasmasphere 90 O -> Very weak “Head and Shoulders” L=4.0 L=5.0 L=5.8 Work done by Z. Hong, 2014 LANL SW Summer School Kp ≤ 1+

10 U N C L A S S I F I E D Slide 10 Operated by the Los Alamos National Security, LLC for the DOE/NNSA AGU Chapman Conference, Jeju, South Korea, August 31 – September 5, 2104 PAD comparison under different Kp (HOPE E=5 keV) – Sample PADs Inside Plasmasphere -> Outside Plasmasphere 90 O -> Weak “Head and Shoulders” L=4.0 L=5.0 L=5.8 Work done by Z. Hong, 2014 LANL SW Summer School 1+ < Kp ≤ 3+

11 U N C L A S S I F I E D Slide 11 Operated by the Los Alamos National Security, LLC for the DOE/NNSA AGU Chapman Conference, Jeju, South Korea, August 31 – September 5, 2104 PAD comparison under different Kp (HOPE E=5 keV) – Sample PADs Not enough statistics! L=4.0 L=5.0 L=5.8 Work done by Z. Hong, 2014 LANL SW Summer School Kp > 3+

12 U N C L A S S I F I E D Slide 12 Operated by the Los Alamos National Security, LLC for the DOE/NNSA AGU Chapman Conference, Jeju, South Korea, August 31 – September 5, 2104 Two Spacecraft Event Selection – Criteria Statistical Chorus Occurrence Starts before midnight towards dawn, outside Plasmasphere. Compare RBSP Spacecraft at 0-2 MLT and MLT, when both are near L= Drift paths for electrons 5-40 KeV approximate circular in this sector. Drift times for 4hrs MLT: 35 keV ~ 1 hour 5 keV ~ 10 hours (max radial deviation 0.25 Re) UBK, Dipole / Volland-Stern, KP=3 Mededith, Ae = KeV 5 KeV

13 U N C L A S S I F I E D Slide 13 Operated by the Los Alamos National Security, LLC for the DOE/NNSA AGU Chapman Conference, Jeju, South Korea, August 31 – September 5, 2104 Two Spacecraft Event Selection – Very few events Used first year of HOPE pitch angle data – launch to 09/23/2013 (there is a reason…) A at later MLT wrt to B: :42 to : :40 to : :44 to : :42 to :25 4 B at later MLT wrt to B: :05 to : :02 to : :58 to : :10 to : :11 to :45 5 SUN

14 U N C L A S S I F I E D Slide 14 Operated by the Los Alamos National Security, LLC for the DOE/NNSA AGU Chapman Conference, Jeju, South Korea, August 31 – September 5, 2104 Chorus at A, no chorus at B :10 to 12:41 Pitch angle distribution peaked at 90 at B at 9E6 reduced to 3.7E6 at A ~ 41 % loss RBSP B 5.2keV RBSP A 5.2keV

15 U N C L A S S I F I E D Slide 15 Operated by the Los Alamos National Security, LLC for the DOE/NNSA AGU Chapman Conference, Jeju, South Korea, August 31 – September 5, 2104 LEO particle precipitation proxy for high altitude wave distribution and intensity (Y. Chen, LANL) Comparing CRRES wave statistics with NOAA 30 KeV precipitation statistics – deriving model relationship

16 U N C L A S S I F I E D Slide 16 Operated by the Los Alamos National Security, LLC for the DOE/NNSA AGU Chapman Conference, Jeju, South Korea, August 31 – September 5, 2104 Proxy for waves for 6hr period centered around :30UT v. “best guess”

17 U N C L A S S I F I E D Slide 17 Operated by the Los Alamos National Security, LLC for the DOE/NNSA AGU Chapman Conference, Jeju, South Korea, August 31 – September 5, 2104 No chorus at A, no chorus at B :14 to 06:51 Pitch angle distribution peaked at 90 at B at 9E6 reduced to 3.7E6 at A ~ 59% loss RBSP B 5.2keV RBSP A 5.2keV

18 U N C L A S S I F I E D Slide 18 Operated by the Los Alamos National Security, LLC for the DOE/NNSA AGU Chapman Conference, Jeju, South Korea, August 31 – September 5, 2104 Proxy for waves for 6hr period centered around :30UT

19 U N C L A S S I F I E D Slide 19 Operated by the Los Alamos National Security, LLC for the DOE/NNSA AGU Chapman Conference, Jeju, South Korea, August 31 – September 5, 2104 Two Spacecraft Event Summary A or B at 0-2 MLT, L=4.5-5, 5 keV electrons A at later MLT wrt to B: :42 to 10:14 – B in Plasmasphere / structured hiss; A in Plasmasheet boundary :40 to 13:11 – Both outside Plasmasphere, No chorus at B, chorus at A, 59% reduction :44 to 07:21 – Both outside Plasmasphere, No chorus at both, same flux :42 to 10:25 – Both in Plasmasphere, close to plasmapause B at later MLT wrt to B: :05 to 11:38 – Both outside Plasmasphere, No chorus at A, chorus at B, 75% reduction No LEO NOAA data :02 to 08:49 – Both in Plasmasphere, B sees broadband Hiss, A observes no hiss :58 to 11:49 – A in Plasmasheet, with chorus; B in Plasmasphere, hiss :10 to 05:45 – A in Plasmasphere / structured hiss; B in Plasmasheet, no chorus :11 to 08:45 – A in Plasmasphere / curious hiss?; B in Plasmasheet, no chorus

20 U N C L A S S I F I E D Slide 20 Operated by the Los Alamos National Security, LLC for the DOE/NNSA AGU Chapman Conference, Jeju, South Korea, August 31 – September 5, 2104 Study Bonus – Curious Hiss observation Hiss rising tone 2 -4 KHz ~4 min repetition

21 U N C L A S S I F I E D Slide 21 Operated by the Los Alamos National Security, LLC for the DOE/NNSA AGU Chapman Conference, Jeju, South Korea, August 31 – September 5, 2104 Summary / Conclusion Statistical Study: 35 keV: Statistically little variation with Kp. Outside plasmasphere persistent “head and shoulder” distributions – evidence for enhanced PA diffusion at more field-aligned pitch angles. Little variation with MLT 5 keV: Statistically very little variation with Kp. Little variation with MLT, mainly 90 o peaked distributions – surprising given the long drift times and local time distribution of waves. HOPE data still incomplete for coverage at all MLT (noon time sector not covered).

22 U N C L A S S I F I E D Slide 22 Operated by the Los Alamos National Security, LLC for the DOE/NNSA AGU Chapman Conference, Jeju, South Korea, August 31 – September 5, 2104 Summary / Conclusion Drift – matching case studies: Show measureable depletion of 5 keV electrons in the presence of waves. Very little change in pitch angle distribution shape – what is maintaining anisotropy? No evidence of development of “head and shoulders” distribution as seen in statistics. Study offers opportunity to quantitatively test predictions of wave-particle interaction theory. Future extension of work to use more sophisticated drift matching calculations and extend work to larger energy range.


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