INJECTION OF SHEAR ALFVEN WAVES IN THE INNER RADIATION BELT USING ARECIBO
Dennis PapadopoulosUniversity of Maryland, College Park
The Seventeenth Annual RF Ionospheric Interactions Workshop
17-20 April 2011Santa Fe, New Mexico
Acknowledge Contributions:UMCP: Xi Shao, B. Eliasson, S. SharmaBAE Systems AT: C.L.Chang, I. Doxas, J. Lebinsky
MHD WAVES - SA
SHEAR ALFVEN (SA)
€
ω /kz = VA , r V g = VA
ˆ b
M ≡ (∇⊥×r E ⊥)⋅
ˆ b = 0
Q ≡∇⊥⋅r E ≠ 0
k
E
B
b
Svg
FAC
Propagation SA Waves – Ionospheric Alfven Resonator (IAR)
)( h
Vn A
R
ω
k
E
B
b
SvgSA wave is guided along the B field
Reflections create standing wave structure
Notice
b·B=0
Natural SA waves
Fabry-Perot like Resonator
Cash et al. 2006
Reflection due to grad h
k
E1
Bo
Magnetosonic Alfven Wave (compressional)
Bo
Propagation MS Waves Alfvenic Duct
D/E Region Ejet
F-peak
SA and MS wave Equations
€
ε∂∂t
+ σ P
⎛
⎝ ⎜
⎞
⎠ ⎟Q = −σ HM −
∂Jz
∂z, ε
∂
∂t+ σ P
⎛
⎝ ⎜
⎞
⎠ ⎟M = σ HQ −
1
μ0
∇2Bz +1
B0
∇⊥2 δp⊥,
∂Bz
∂t= −M , μ0
∂Jz
∂t= −
∂Q
∂z+∇⊥
2 Ez , ε 0
∂
∂t+ σ ||
⎛
⎝ ⎜
⎞
⎠ ⎟Ez = Jz , .
€
ε(z ) =c2
VA2(z )[1 +ν in
2 (z )/ Ωi2 ]
€
Q =∇⊥⋅ E⊥, M = ∇⊥ × E⊥( )⋅ i z , Jz = (∇⊥ × B⊥)⋅ i z
SAW M=0MS Q=0
Lysak 1998
MS-SW Wave CouplingLow Latitude Pc1
1.AIC instability due to proton anisotropy drives SA waves at high L-shells
2. SA partly mode converted by Hall to MS propagate in Alfvenic duct to lower latitude
3. Ground signature due to Hall current driven by the MS interaction with E-region
KEY OBSERVATION: NO SAW OR EMIC WAVES IN INNER RB AND SLOT
.1-5 Hz
RADIATION BELTS
REGIONS
PARTICLE LIFETIMES
Wave particle Interactions (WPI) Pitch Angle Diffusion (PAD)
Radiation Belts – Inner - Outer
Protons Electrons
PARTICLE FLUX LEVEL -> BALANCE OF INJECTION TO TRANSPORT AND PRECIPITATION (WPI) RATE Pitch angle diffusion (PAD)
slot
WPI-PAD CONTROL OF LOSS RATE
ULF/ELF/VLF waves resonate with trapped particles in the magnetosphere causing pitch angle scattering and precipitation. B0
trapped
€
ω −kzvz = nΩ
kzvz ≈ ±Ω
Inner Proton Belt
Typical inner belt proton lifetimes: 10 MeV – decades50 MeV – century
SA Wave BoundaryNo SA Waves
Proton Lifetimes in the Inner Belt are Long
Typical inner belt proton lifetimes: 10 MeV – decades100 MeV – centuries1000 MeV – millennia
South Atlantic Anomaly
Over the south Atlantic, the inner proton belt is closest to the surfaceProtons in this region are the largest radiation source for LEO satellites
Active Probing of Inner RB Using the Arecibo Heater
Arecibo
South Atlantic Anomaly
RBSP
WPI critical aspect of RB physics. RBSP will study interactions in the natural environment, A wave injection facility at Arecibo at frequencies that resonate with energetic protons and electrons offer cause and effect understanding of the induced transport processes with RBSP
Focus on SAW for protons
and EMIC for electrons
Frequency Selection for Protons
Example for L=1.5
2
( , )cos 2
z p
z A
A
k V
k V
MVE
E
ω
ω
ω
Frequency Selection for Resonance of Protons with SAW
Fill tube with SAW
Frequency requirement for equatorial resonance with SAW at L=1.5
Frequency range 5-30 Hz
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
ω ωωω ω ω ω
ωω
ENERGETIC ELECTRON WP INTERACTIONS DUE TO EMIC WAVES
Summers et al., 1998, 2000, 2003
Outer Belts
Frequency Selection for Electrons EMIC
Summers et al., 1998, 2000, 2003
Outer Belts
For midlatitude MeV electronsHelium
branch
<<n We
>>n We
J
Hall
JPedersen
Bo
SA Wave Generation During Electrojet PEJ Anenna
e
εω
/ /P H en e
en e
J J
T
E
+ +
+ +
+
+ +
+ +
+
I I
I I
I I
I
Eo
Injects whistlers and SAW
heater
E
H
TEM mode
Near field Far field
FAC
0<t<T
0 T<t<2ToE E
E
T
Bottom of the ionosphere=ew s
MHD Wave Generation by the PEJ
• SA waves can be detected: (a) In the near zone below the heated spot and (b) By satellites over-flying the heated spot but confined to the magnetic flux tube that spans the heated spot (c) Through the EI waveguide for f>8 Hz (Schumann Resonance)
PEJ
SA will be guided by the magnetic field to the conjugates – No lateral
propagation through the plasma
Evanescent in EI Waveguide if f<8Hz
/ 2 8Ef c R Hz Schumann
ULF Signal Propagation Evanescent Mode (1 Hz)
• 28 April, 2007 UTC 05:01:00 – 05:05:45• HAARP at 2.88 MW and 3.3 MHz• Detected 1 Hz & 3 Hz peaks• B~1/R2 wave evanescent (Frequencies below Schumann
Resonance)
9.9 pT .28 pT
Gakona Juneau – 800 km
Frequency .2 Hz
Closest distance 80 km
Detection time 25 sec
Detection distance 150 km
1.5 pT on the ground
SAW DEMETER Detection
BeforeAfter
.2 Hz
Excitation of the IAR due naturally excited waves at .25 Hz and .5 Hz and by HAARP generated SA at 1.0 Hz.
IAR Excitation by the PEJ
MS Wave
Ionospheric Current Drive (ICD) Concept
2exp( )
B pJ i t
B
ω 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
Model of CID for Vertical B
€
ε∂∂t
+ σ P
⎛
⎝ ⎜
⎞
⎠ ⎟Q = −σ HM −
∂Jz
∂z, ε
∂
∂t+ σ P
⎛
⎝ ⎜
⎞
⎠ ⎟M = σ HQ −
1
μ0
∇2Bz +1
B0
∇⊥2 δp⊥,
∂Bz
∂t= −M , μ0
∂Jz
∂t= −
∂Q
∂z+∇⊥
2 Ez , ε 0
∂
∂t+ σ ||
⎛
⎝ ⎜
⎞
⎠ ⎟Ez = Jz , .
€
ε(z ) =c2
VA2(z )[1 +ν in
2 (z )/ Ωi2 ]
€
Q =∇⊥⋅ E⊥, M = ∇⊥ × E⊥( )⋅ i z , Jz = (∇⊥ × B⊥)⋅ i z
Lysak 1998
ICD vs. PEJ How to Distinguish2 kHz as ejet proxy
102
103
104
0
0.2
0.4
0.6
0.8
1
1.2A
vera
ge
Fie
ld L
evel
No
rmal
ized
to 2
kH
z
frequency [Hz]
3.3 MHz Heating
EISCAT 2002 HAARP
B (2 kHz)
B(U
LF)/
B(2
kHz)
.5
ICD
PEJ
Papadopooulos et al. GRL 2005
ICD Further PoP Tests
Electrojet Modulation
Current Drive
(Gakona) ULF VS 1 kHz Amp.All Times [04/28/2008 21:00:00 - 05/04/2008 09:20:00]
1 kHz Amplitude (pT)
0.0 0.5 1.0 1.5 2.0 2.5
UL
F A
mp
litu
de
(pT
)
0.0
0.5
1.0
1.5
2.0
2.5
(Gakona) ULF VS 1 kHz Amp.All Times [04/28/2008 21:00:00 - 05/04/2008 09:20:00]
1 kHz Amplitude (pT)
0.0 0.5 1.0 1.5 2.0 2.5
UL
F A
mp
litu
de
(pT
)
0.0
0.5
1.0
1.5
2.0
2.5
5/2008
9/2009
Ejet Current Strength
Proof of Concept ICD Experiment – Conducted under DARPA/BRIOCHE
Chang-Lebinsky-Milikh-Papadopoulos
2.8 MHz, O-mode
ELF detection at Distant Sites
• Distance to Gakona– Lake Ozette, WA (W)
• 1300 mi– Hawaii (H)
• 2900 mi– Guam (G)
• 4800 mi• Detection under quiet Gakona cond.• No detection during electrojet days
Oct. 22-23
Implications of ICD to RB and RBR – Potential Arecibo Tests
Eliasson-Papadopoulos: Oblique model includes spontaneous B field generation
Bt (c /ne)n T
HF heating
SAW injection
Papadopoulos and Chang GRL, 1985
B
Ground B field
B field at 90 km
Summary
• HAARP experiments have helped transition ofof cartoon HF low frequency current drive in the ionospheric plasma to reality.
• The physics understanding of ICD provided by HAARP allows for active probing of the physics controlling the inner radiation belt and could lead to techniques that can actively reduce the flux of trapped proton and electrons.