FUNDAMENTAL PHYSICS ISSUES ON RADIATION BELTS AND REMEDIATION

MURI HighlightsDennis Papadopoulos

University of Maryland, College Park

Interim ReviewDecember 12, 2010San Francisco, CA

Acknowledge Contributions:BAE Systems AT: C.L.Chang, I. Doxas, J. LebinskyNRL: M. Lampe, G. Ganguli, J. Huba

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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

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Methodology-Resources

HAARP DEMETER

DMSPCONJUGATE BUOYS

LAPD

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

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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

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.

DemeterStanford

MURI Challenge: Inject ELF using HF without needing an electrojet

Ionospheric Current Drive (ICD) Concept

2exp( )

B pJ i t

B

Step 1: MS Wave

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

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

=-90o

MS SAWt= .56 sec

MS SAWt=4.6 sec

Ionospheric Model

Ground B Field

Proof of Concept ICD Experiment – Conducted under DARPA/BRIOCHE

Chang-Lebinsky-Milikh-Papadopoulos

2.8 MHz, O-mode

Implications of ICD to RB and RBR – Potential Arecibo Tests

Eliasson-Papadopoulos: Oblique model includes spontaneous B field generation

Bt (c /ne)nT

HF heating

SAW injection

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

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

Papadopoulos and Chang GRL, 1985

B

Ground B field

B field at 90 km

Ganguly-Gordon-Papadopoulos PRL 1985

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

EjetQuiet

ICD

ICD

ICD

ICD

ICD

ICD

ICD

ICD

PEJ

PEJ

ULF-ELF (12-49 Hz) Thick BarsELF-VLF (500-8K Hz) Thin Lines

M≈5x109 A-m2

Results of DARPA/BRIOCHE Campaign Chang- Papadopoulos

ICD Scaling with Geomagnetic Latitude

E

Σ = 5 S

Σ =500 S

B

h

M≈Lh~

Secondary antenna efficiency40 dB higher in equator

Cowling effect

Dip Equator

ICD Scaling with Geomagnetic Latitude

B

h E

I

Hall Conductance vs. Geomagnetic Latitude

HAARP

Meff ILh (EL)Lh

Meff () (5 109)[()

5S](

PHF3.6MW

)A m2

(2.7 108)()(PHF /MW )A m2

For PHF=500 kW we get Meff≈6x1010 A-m2 at ≈Meff≈1.5x1010 A-m2 at ≈

For PHF=500 KWM=6x1010 A-m2

M=1.5x1010 A-m2

Implications - Barge or Shipboard Option

High Latitude

10 MHz

1 MHz

Equator

Strawman HF Array

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

4 MHz

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

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

option

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

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

Orbiting satellite carrying superconducting or permanent magnet

Controlling its spin results in injection of SAW in the

RB

SAW

SAW

B

M

SAW

Ground

Ion

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

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

• 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

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 resulting in increase of their precipitation rate.

B0

trapped

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

Briefed to DARPA Director and AF Deputy Assistant Secretary Steve Walker

2 22 2 3

21

2 2

2

/

1( | |) ( )

for

As a result 1/ / before

reaching resonance (1/ 0)

z z e

pe pj

je j

j

z e z

z

k v

k c

k c

k v

k

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

See Moralles (UCLA) talk

Priority in option phase

LAPD

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

≠

Starks, et al. (2008)“Anomalous Absorption”Good word but what is the underlying physics

(what do we hide under rug?)

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

Q6: How reliably can we generate ionospheric ducts?

Code validation – See Milikh (UMCP)Experiments conducted under

DARPA/BRIOCHE

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

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)

Q10: What types of waves create the slot?

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)

Combine lightning and Demeter data