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FUNDAMENTAL PHYSICS ISSUES ON RADIATION BELTS AND REMEDIATION. MURI Highlights. Dennis Papadopoulos University of Maryland, College Park. Acknowledge Contributions: DARPA/BRIOCHE Program BAE Systems AT: C.L.Chang, I. Doxas, J. Lebinsky NRL: M. Lampe, G. Ganguli, J. Huba. Interim Review

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slide1

FUNDAMENTAL PHYSICS ISSUES ON RADIATION BELTS AND REMEDIATION

MURI Highlights

Dennis Papadopoulos

University of Maryland, College Park

Acknowledge Contributions:

DARPA/BRIOCHE Program

BAE Systems AT: C.L.Chang, I. Doxas, J. Lebinsky

NRL: M. Lampe, G. Ganguli, J. Huba

Interim Review

December 12, 2010

San Francisco, CA

overarching objectives
OVERARCHING OBJECTIVES
  • TECHNICAL
    • DEVELOP QUANTITATIVE MODELS OF THE LOSS RATE OF ENERGETIC PARTICLES IN THE INNER RADIATION BELTS AND TEST AGAINST OBSERVATIONS
    • ASSES AND TEST CONCEPTS FOR CONTROLLED INJECTION OF VLF/ELF/ULF WAVES IN THE RB FROM GROUND AND SPACE PLATFORMS
    • PROVIDE THE PHYSICS UNDERPINNINGS THAT CAN LEAD TO ACTIVE CONTROL THE ENERGETIC PARTICLE FLUX TRAPPED IN THE RADIATION BELTS (RBR ; PRBR)
  • EDUCATIONAL
    • DEVELOP THE SCIENTIFIC AND ENGINEERING MANPOWER WITH THE INTERDISCIPLINARY SKILLS REQUIRED TO ADDRESS FUTURE MAJOR TECHNICAL ISSUES OF NATIONAL SIGNIFICANCE

2

methodology resources

DEMETER

HAARP

LAPD

CONJUGATE BUOYS

DMSP

Methodology-Resources

TOPICS ADDRESSED BY AN INTERPLAY OF THEORY/COMPUTATION, LABORATORY EXPERIMENTS, FIELD EXPERIMENTS, SATELLITE MEASUREMENTS ANDDATA ANALYSIS

3

physics and technology challenges
PHYSICS AND TECHNOLOGY CHALLENGES
  • Radiate- Inject efficiently from space or ground VLF/ELF/ULF waves in the RB
    • Ionospheric Current Drive (ICD)
    • Performance of electric dipole antennas at VLF in plasmas (DSX - AF)
    • VLF generation in RB by injection of low ionization chemicals -
    • Innovative Injection Concepts – Rotating Magnetic Field (RMF)
  • Propagate – Guide waves to regions of enhanced RB
    • Injection to naturally occurring ducts
    • Generation of artificial ducts by ionospheric heaters (HAARP)
    • The missing 20 dB puzzle
  • Amplify – Use the free energy stored in trapped energetic particles to amplify the VLF wave power
    • The physics of Artificially Stimulated Emissions
    • Optimizing conditions for ASE
  • Precipitate – Physics of particle precipitation with Wave Particle Interactions (WPI)
    • The physics of slot formation
    • The physics of energetic proton loss
    • How to precipitate without requiring resonance

4

slide5

Q1. Can we use ground HF to inject ELF in the relevant regions of the RB?

Current Status: Need the presence of an electrojet – Polar Electrojet (PEJ) Ant.

Stanford

Demeter

MURI Challenge: Inject ELF using HF without needing an electrojet

Ionospheric Current Drive (ICD) Concept

MS Wave

Step 1:

Step 2:

E field of MS wave drives Hall current in E-region resulting in secondary antenna resembling PEJ

Injects SAW upwards and ELF in the Earth-Ionosphere Waveguide

slide6

ICD

Modeling:

Generalize and modify Bob Lysak’s code ( Lysak ,1997.)

Ionospheric Model

Ground B Field

q=-90o

t= .56 sec

MS

t=4.6 sec

SAW

MS

SAW

slide8

Proof of Concept ICD Experiment – Conducted under DARPA/BRIOCHE

Chang-Lebinsky-Milikh-Papadopoulos

2.8 MHz, O-mode

slide10

Implications of ICD to RB and RBR – Potential Arecibo Tests

Eliasson-Papadopoulos: Oblique model includes spontaneous B field generation

Papadopoulos and Chang GRL, 1985

B

B field at 90 km

SAW injection

Ground B field

HF heating

Concept to be tested experimentally as soon as Arecibo transmitter becomes operational. Radiation Probes could provide diagnostics

Ganguly-Gordon-Papadopoulos PRL 1985

slide11

ICD

ICD

Quiet

Ejet

ICD

ICD

ICD

ICD

ICD

ICD

PEJ

PEJ

Implications of ICD to Navy ELF Communications:

Invited by Dr. Junker (ONR) to brief the National Naval Responsibility (NNR) Underwater Communications Technical Panel

Key items: 1. ICD can provide ELF at all times and at all latitudes

2. It can provide a ship-towed mobile ELF system

M≈5x109 A-m2

Results of DARPA/BRIOCHE Campaign

Chang- Papadopoulos

icd scaling with geomagnetic latitude

Σ =

500 S

ICD Scaling with Geomagnetic Latitude

Dip Equator

Cowling effect

Σ = 5 S

B

M≈SELh~S

h

E

Secondary antenna efficiency

40 dB higher in equator

icd scaling with geomagnetic latitude1
ICD Scaling with Geomagnetic Latitude

For PHF=500 KW

M=6x1010 A-m2

M=1.5x1010 A-m2

I

E

Hall Conductance vs. Geomagnetic Latitude

HAARP

B

For PHF=500 kW we get Meff≈6x1010A-m2 at l≈0

Meff≈1.5x1010 A-m2 at l≈6°

h

implications barge or shipboard option
Implications - Barge or Shipboard Option

Combination of low HF power and high HF frequency requirements allow for mobile option

High Latitude

  • Strawman HF Array
  • HF frequency 8-10 MHz
  • Linear polarization
  • Twenty 25-kW solid state transmitters
  • Ship provided power

4 MHz

Equator

10 MHz

  • Can provide theater and strategic sub communications
  • Enhance Blue-Green laser tactical communications by providing info as to transmit and receive locations

1 MHz

slide15

ICD Emerged as a new as well as novel technology for using ground based HF to inject SAW in the RB as well as an important contributor to underwater communications and other DoD applications

DARPA/BRIOCHE and ONR/MURI Collaboration a Key ingredient of success

slide16

Q2: Can we use Rotating Magnetic Fields to Radiate Efficiently in Space Plasmas and if so what is the use ?

MURI challenge: Use LAPD experiments in conjunction with theory/modeling to understand the efficiency and utility of RMF antennas

1. Efficient SAW generation

  • Satellites carrying magnets use their spin to inject SAW in RB
  • RM on ground can inject SAW in the RB

SAW

SAW

Orbiting satellite carrying superconducting or permanent magnet

Controlling its spin results in injection of SAW in the RB

Ion

B

M

SAW

Ground

slide17

Q2: Can use Rotating Magnetic Fields to Radiate Efficiently in Space Plasmas and if so what is the use ?

MURI challenge: Use LAPD experiments in conjunction with theory/modeling to understand the efficiency and utility of RMF antennas

2. Transverse Bw does not vary with time - gradB

Q3: Can we break the electron adiabatic invariance without the need of cyclotron resonance ?

See Gekelman and Sharma presentations

slide18

B0

trapped

An array of superconducting magnets, located at selected footprints of the field lines rotating at 1-30 Hz rate inject Alfven waves into the RB. These waves interact resonantly with the trapped energetic protons resultingin increase of their precipitation rate.

Q4: Is it possible to consider a combined ground based RBR and PRBR system?

PRBR Concept – Motivated by vulnerability of submicron based electronics to energetic protons

  • Inject ULF (1-30 Hz) waves from the ground into the Proton Radiation Belt (L~1.5-1.8 shells) to cause Pitch Angle Diffusion (PAD) and increase proton precipitation

Briefed to DARPA Director and AF Deputy Assistant Secretary Steve Walker

slide19

Ground Based RBR concept similar system with PRBR but relies on EMIC waves

Frequencies 10-70 Hz

There have never been any EMIC studies in the laboratory

Priority in option phase

LAPD

See Moralles (UCLA) talk

slide20

Q5: What physics causes the “20 dB puzzle”?

“Anomalous Absorption”

Good word but what is the underlying physics

(what do we hide under rug?)

Starks, et al. (2008)

Talks by Scales (VT), Wang (USC), Faust (SU) and Shao (UMCP)

slide21

Q6: How reliably can we generate ionospheric ducts?

Experiments conducted under

DARPA/BRIOCHE

Code validation – See Milikh (UMCP)

Ion density measured at 670 km by DEMETER overflying HAARP MZ (connected points) along with the numerical modeling (color traces).

Ion density, fraction of O+ ions, and vertical ion velocity measured by two DMSP satellites overflying HAARP MZ at 850 km.

Spin off – HF focusing -> See Vartanyan (UMCP)

slide22

Q7: Are there ways to increase the probability of amplification?

Theoretical and experimental studies using chirping

Q8: How good are our models of ducted whistler propagation ?

Q9: How important is the Ionospheric Alfven Resonator (AIR) ?

See Presentation by Anatoly Streltsov (Dartmouth)

slide23

Q10: What types of waves create the slot?

Combine lightning and Demeter data

Talk by Gemelos (SU)

Q11: What is the radiation efficiency of high voltage electric dipoles in the plasmasphere at whistler frequencies ?

Update by Qiu (SU)

slide24

Thanks etc – This is an interim review of the MURI whose purpose is less to show off the MURI’s achievements and more to take a deep breath, look at what we have been doing and select the challenges that need to finish in our final year.

Given our time constraints I will try to be brief and with the exception of one, essentially highlight some of the challenges we set out to address, let the MURI performers tell their more detailed story.

As a reminder the overarching objectives of the MURI were…..

and the methodology is illustrated in …..

As before the physics issues were grossly divided in Radiate, Propagate, Amplify and Precipitate.

I will highlight some of the issues associated with them in the form of questions that we are trying to resolve and their relevance.

Structure of presentation in form of key questions

slide25

Objective: Use ground based HF to inject ULF/ELF/VLF waves in the RB in order to induce energetic particle precipitation

Current Solution: Modulate ejet currents flowing in the D/E region using electron heating by modulated HF injection (PEJ)

Problem: Ejets do not connect to field lines of interest for RBR.

Challenge: Is it possible to use HF to drive currents in the ionosphere freeing the process from its dependence on ejet?

MURI provided the fundamental concept of ICD – Experimental PoP conducted under DARPA/BRIOCHE (C.L. Chang PI)

low elf observed by demeter satellite
Low ELF Observed by Demeter Satellite

2010-11-06, 06:15:00-06:34:30 ELF 11 Hz modulation (O-MZ)

  • 11Hz showed along track near HAARP, not before/after
  • Duration: 17s or 130 km
  • Peak Ey ~ 0.08 (mV/m)2/Hz > Bx ~ 0.25 pT in free space, comparable to ground value

BRIOCHE QPR4 NOV 2010 26

low elf observed by demeter satellite1
Low ELF Observed by Demeter Satellite

2010-11-06, 06:15:00-06:34:30 ELF 11 Hz modulation (O-MZ)

  • Gakona: clear signals on the ground
    • NS: 0.2 pT; EW: 0.05 pT
  • Poker Flat: no signal on the ground

BRIOCHE QPR4 NOV 2010 27

slide28

Low ELF Observed by Demeter Satellite

  • This event occurred at quiet time with sporadic E layer
  • ICD at E layer ?
  • No magnetic activities, no electrojet
  • Low ionospheric absorption

BRIOCHE QPR4 NOV 2010 28

oct nov 2010 brioche campaign elf poker flat
Oct-Nov 2010 BRIOCHE Campaign: ELF - Poker Flat
  • Poker Flat received a number of ELF signals in 11 – 49 Hz range
  • Poker ELF: EW > NS vs. Gakona ELF: NS > EW
  • Gakona to Poker amp. reduced by 15 – 20 times

BRIOCHE QPR4 NOV 2010 29

slide30

Superconducting RMF with 1 m length, .1 m2 area, 1.5 x 104 turns gives 105-106 A-m2

nT at 1 km

Spinning satellite with magnetic structure can act as as antenna – Cube sats