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Magnetic Reconnection and Turbulence in Stellar-Convective-Zone-Relevant
Laboratory Plasmas
Jack D. Hare
MAGPIE
MAGPIE: S. V. Lebedev, L. G. Suttle, S. N. Bland, T. Clayson, J. W. D. Halliday, S. Merlini, D. R. Russell, F. Suzuki-Vidal, E. R. Tubman, V. Valenzuela-Villaseca
CERBERUS: R. A. Smith, S. Eardley, T. Robinson, N. StuartGORGON: J. Chittenden, N. Niasse
with N. F. Loureiro (MIT) and A. Ciardi (Sorbonne)
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Summary
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Magnetic Reconnection with Plasmoids MHD Turbulence
New Diagnostics for Turbulence PUFFIN: A new pulser at MIT
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Current sheet
BB
Magnetic Reconnection
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Current sheet
BB
Magnetic Reconnection
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Prediction: 1000 yrs. Reality: 10 minutes!
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Plasmoids Lead to Fast Reconnection and Anomalous Heating
Stronglysheared flows
Multiple current sheets
Overview of recent theory:Loureiro, N. F., & Uzdensky, D. A. (2015). PPCF, 58, 014021
BB
Current sheet
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Plasmoids Lead to Fast Reconnection and Anomalous Heating
Stronglysheared flows
Multiple current sheetsBB
Current sheet
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The Convective Zone is a Collisional Plasma (and so is a Z-Pinch)
β’ Collisionless: Solar Flares, MRX, TREX
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πΏ β« πππ >π
πππβ«
π
πππβ«
π£πππππ
πΏ β«π
πππβ«
π
πππ> πππ >
π£πππππ
β’ Collisional: Convective zone, Z-pinch
D. D. Ryutov, IEEE TPS (2015)
Kelvinsong / CC BY-SA
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Outline
β’What is magnetic reconnection?
β’Reconnection and Diagnostics on the MAGPIE generator
β’Anomalous heating and the Plasmoid Instability
β’Creating turbulence through flux tube merging
β’Diagnostics for turbulence
β’ The PUFFIN facility
Pulsed Power Driven Reconnection, [email protected] 8
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Laboratory Reconnection Experiments
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Reconnection Layer
Laserspot
BubbleExpansion
Magnetic Ribbon
Magnetically Driven:B=0.03 T, ne=5x1013 cm-3,
V=10 km/s, L= 10 cmTe= 10 eV, Ti= 10 eV
Ξ²th<<1, Ξ²dyn<<1Long lasting
Laser Driven:B=50 T, ne=7x1019 cm-3,V=500 km/s, L= 0.1 cm,Te= 650 eV, Ti= 250 eV
Ξ²th>>1, Ξ²dyn>>1Transient
Pulsed Power Driven:B=3 T, ne=5x1017 cm-3,V=50 km/s, L= 1 cm
Te= 100 eV, Ti= 500 eV,
Ξ²th βΌ 1, Ξ²dyn βΌ 1Long lasting
Reconnection layer
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The MAGPIE Pulsed Power Generator
β’ Constructed 1993
β’ 4 Marx banks: 300 kJ
β’ 1.4 MA peak current
β’ 250 ns rise time
β’ 1 TW into 1 cm3
MAGPIE
Load goes here
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Lebedev et al, Rev. Mod. Phys (2019)
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Plasma Source: Exploding Wire Array
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Current
I=1.4 MA, 240 ns rise time
Dime for scale
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Plasma Source: Exploding Wire Array
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Current
B
V
I=1.4 MA, 240 ns rise time
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Magnetic Reconnection Setup: Double Exploding Wire Arrays
1.4 MA
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Suttle, L.G. et al. PRL 2016Hare, J. D. et al. PRL 2017Suttle, L.G. et al. PoP 2017Hare, J. D. et al. PoP 2018Hare, J. D. et al. PoP 2018
β’ Sustained flows
β’ Quasi-2D
β’ Collisional
β’ No guide field
Pulsed Power Driven Reconnection, [email protected]
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Magnetic Reconnection Setup: Double Exploding Wire Arrays
β’ Sustained flows
β’ Quasi-2D
β’ Collisional
β’ No guide field
Suttle, L.G. et al. PRL 2016Hare, J. D. et al. PRL 2017Suttle, L.G. et al. PoP 2017Hare, J. D. et al. PoP 2018Hare, J. D. et al. PoP 2018
14Pulsed Power Driven Reconnection, [email protected]
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Overview of Diagnostic Suite
Pulsed Power Driven Reconnection, [email protected] 15
2 m
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Overview of Diagnostic Suite
Pulsed Power Driven Reconnection, [email protected] 16
2 m
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Diagnostic Setup
17
y
x
y
x
G. F. Swadling et al. RSI (2014)
Pulsed Power Driven Reconnection, [email protected]
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Diagnostic Setup
18
y
x
y
x
G. F. Swadling et al. RSI (2014)
Pulsed Power Driven Reconnection, [email protected]
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Diagnostic Setup
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z
x
z
x
y
x
y
x
G. F. Swadling et al. RSI (2014)
Pulsed Power Driven Reconnection, [email protected]
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End on Electron Density (Laser Interferometry)
Pulsed Power Driven Reconnection, [email protected]
y
x 20
Wires
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End on Electron Density (Laser Interferometry)
Pulsed Power Driven Reconnection, [email protected]
y
x 21
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End on Electron Density (Laser Interferometry)
Pulsed Power Driven Reconnection, [email protected]
y
x
A plasmoid
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Pulsed Power Driven Reconnection, [email protected]
Magnetic Field Profile (Faraday Rotation Imaging)
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z
x
10 mm
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Magnetic Field Profile (Faraday Rotation Imaging)
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z
x Pulsed Power Driven Reconnection, [email protected]
10 mm
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Magnetic Field Profile (Faraday Rotation Imaging)
B B
25
z
x Pulsed Power Driven Reconnection, [email protected]
πΌ(π₯, π§) β ΰΆ±πππ©. ππ
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B B
Magnetic Field Profile (Faraday Rotation Imaging)
Harris Sheet:
1 mm
z
x
G. F. Swadling et al. RSI (2014)
πΌ(π₯, π§) β ΰΆ±πππ©. ππ
26Pulsed Power Driven Reconnection, [email protected]
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Velocity and Temperature (Thomson Scattering)
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Fibre Optic Bundle
Fibre Optic Bundle
Pulsed Power Driven Reconnection, [email protected]
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Overall shift: Vfi
Collective scattering from Ion Acoustic Waves
Velocity and Temperature (Thomson Scattering)
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Fibre Optic Bundle
Fibre Optic Bundle
Pulsed Power Driven Reconnection, [email protected]
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Fibre Optic Bundle
Fibre Optic Bundle
Pulsed Power Driven Reconnection, [email protected]
Separation: ZTe
Overall shift: Vfi
Collective scattering from Ion Acoustic Waves
Velocity and Temperature (Thomson Scattering)
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Fibre Optic Bundle
Fibre Optic Bundle
Pulsed Power Driven Reconnection, [email protected]
Width: Ti
Separation: ZTe
Overall shift: Vfi
Collective scattering from Ion Acoustic Waves
Velocity and Temperature (Thomson Scattering)
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Fibre Optic Bundle
Fibre Optic Bundle
Pulsed Power Driven Reconnection, [email protected]
Width: Ti
Separation: ZTe
Overall shift: Vfi
Collective scattering from Ion Acoustic Waves
Velocity and Temperature (Thomson Scattering)
[100 km/s]
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Velocity and Temperature (Thomson Scattering)
Ξ»0
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Fibre Optic Bundle
2 mm
Pulsed Power Driven Reconnection, [email protected]
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Velocity and Temperature (Thomson Scattering)
Ξ»0
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Fibre Optic Bundle
2 mm
Cold (50 eV)Fast movingΞΞ»=0.6 Γ
V=50 km/s
Hot (600 eV)Stationary
ΞΞ»
Pulsed Power Driven Reconnection, [email protected]
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Velocity and Temperature (Thomson Scattering)
Ξ»0
34
Fibre Optic Bundle Cs= 30 km/s, VA= 70 km/s
2 mm
Pulsed Power Driven Reconnection, [email protected]
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Velocity and Temperature (Thomson Scattering)
Ξ»0
35
Fibre Optic Bundle Cs= 30 km/s, VA= 70 km/s
2 mm
Pulsed Power Driven Reconnection, [email protected]
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Power Balance in the Reconnection Layer
Pulsed Power Driven Reconnection, [email protected] 36
ππππΏβ πΈπππ + πΈπππ + πΈπ‘β,π + πΈπ‘β,π β πππ’π‘πΏβ πΈπππ + πΈπ‘β,π + πΈπ‘β,π~50% ~25% ~25% ~40% ~60%
2Ξ΄
2L πππ
πππ’π‘
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Anomalous Heating in the Reconnection Layer
Pulsed Power Driven Reconnection, [email protected] 37
ππππΏβ πΈπππ + πΈπππ + πΈπ‘β,π + πΈπ‘β,π β πππ’π‘πΏβ πΈπππ + πΈπ‘β,π + πΈπ‘β,π~50% ~25% ~25% ~40% ~60%
Οπ£ππ π β 800 ns
Οπππ β 350 ns
Οππ₯π β 50 ns
Classical heating is too slow:
Οππ₯π βͺ Οπ£ππ π, Οπππ 2Ξ΄
2L πππ
πππ’π‘
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Anomalous Heating in the Reconnection Layer
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ππππΏβ πΈπππ + πΈπππ + πΈπ‘β,π + πΈπ‘β,π β πππ’π‘πΏβ πΈπππ + πΈπ‘β,π + πΈπ‘β,π~50% ~25% ~25% ~40% ~60%
Οπ£ππ π β 800 ns
Οπππ β 350 ns
Οππ₯π β 50 ns
Classical heating is too slow:
Οππ₯π βͺ Οπ£ππ π, Οπππ 2Ξ΄
2L πππ
πππ’π‘
Need a faster mechanism:Plasmoids?
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Outline
β’What is magnetic reconnection?
β’Reconnection and Diagnostics on the MAGPIE generator
β’Anomalous heating and the Plasmoid Instability
β’Creating turbulence through flux tube merging
β’Diagnostics for turbulence
β’ The PUFFIN facility
Pulsed Power Driven Reconnection, [email protected] 39
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Plasmoids Visible in Electron Density Maps
Pulsed Power Driven Reconnection, [email protected] 40
Region of enhanced density (a βplasmoidβ): Vy=130 km/s
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Uniformity of Inflows
Pulsed Power Driven Reconnection, [email protected] 41
Uniform inflow density near layer
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Magnetic Structure of Plasmoids
Pulsed Power Driven Reconnection, [email protected] 42
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Magnetic Structure of Plasmoids
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βB-dotβ probe
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Magnetic Structure of Plasmoids
Pulsed Power Driven Reconnection, [email protected] 44
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Magnetic Structure of Plasmoids
Pulsed Power Driven Reconnection, [email protected] 45
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Magnetic Structure of Plasmoids
Pulsed Power Driven Reconnection, [email protected] 46
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Magnetic Structure of Plasmoids
Pulsed Power Driven Reconnection, [email protected] 47
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Plasmoids lead to fast reconnection and anomalous heating
Multiple current sheets
Overview of recent theory:Loureiro, N. F., & Uzdensky, D. A. (2015). PPCF, 58, 014021
BB
Current sheet
Plasmoid instability depends on:β’ π = π0πΏππ΄/πππ
[Lundquist number]β’ πΏ/ππ
[current sheet length]
48Pulsed Power Driven Reconnection, [email protected]
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Stronglysheared flows
Multiple current sheets
Regimes of the Plasmoid instability: Collisional MHD
49Pulsed Power Driven Reconnection, [email protected]
Collisional MHD
Plasmoids
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PlasmoidsStronglysheared flows
Multiple current sheets
Regimes of the Plasmoid instability: The Semi-Collisional Regime
50Pulsed Power Driven Reconnection, [email protected]
Include two-fluid effects
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The Semi-Collisional Plasmoid Instability
Pulsed Power Driven Reconnection, [email protected] 51
Baalrud et al. PoP 2011
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Outline
β’What is magnetic reconnection?
β’Reconnection and Diagnostics on the MAGPIE generator
β’Anomalous heating and the Plasmoid Instability
β’Creating turbulence through flux tube merging
β’Diagnostics for turbulence
β’ The PUFFIN facility
Pulsed Power Driven Reconnection, [email protected] 52
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Flux Tube Merging
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Shading: out of plane currentBlack lines: magnetic flux surfaces
From Zhou, Y. et al. (2004). Rev Mod Phys, 76(4), 1015β1035
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Flux Tube Merging
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From Zhou, Y. et al. (2004). Rev Mod Phys, 76(4), 1015β1035
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Flux Tube Merging
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From Zhou, Y. et al. (2004). Rev Mod Phys, 76(4), 1015β1035
Anisotropy
Power Spectra
Intermittency
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Pulsed-power driven Flux Tube Merging
Wire arrays produce flux tubes during initial ablation
From: Martin et al. PoP 2010
Wire cores
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Flux tubes merge on axis to form a turbulent column
Pulsed-power driven Flux Tube Merging
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Flux tubes
From: Martin et al. PoP 2010
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Optical Self Emission: Formation of a Turbulent Column
Axial imaging
Wires
5 mm
Long lasting, confined column
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Optical Self Emission: Formation of a Turbulent Column
Axial imaging
Wires
5 mm
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Long lasting, confined column
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Dimensionless Parameters
Wires
L = 5 mm
DimensionlessParameters
EstimatedParameters
140 nsne= 5 x 1018 cm-3
Te = 100 eVTi = 200 eVB = 5 TV = 200 km/s
Ξ»ei/L β 0.01Ξ² β 1Re β 2500ReM β 250Pr < 0.1
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Axial Interferometry shows cellular structures
Wires
s0327_185 mm
355 nm laser probing: 200 ns after current startCellular structures
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Side on Shadwography shows cellular structures
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Long lasting, confined column
Cellular turbulentstructures
Imploding Wire Array
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Outline
β’What is magnetic reconnection?
β’Reconnection and Diagnostics on the MAGPIE generator
β’Anomalous heating and the Plasmoid Instability
β’Creating turbulence through flux tube merging
β’Diagnostics for turbulence
β’ The PUFFIN facility
Pulsed Power Driven Reconnection, [email protected] 63
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B
V
Pulsed Power Driven Turbulence, [email protected] 64
A simple experiment: Plasma flow into a planar obstacle
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Imaging Refractometry: Density Fluctuations
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Flow
https://arxiv.org/abs/2007.04682
Flow into planar obstacle
B
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Imaging Refractometry: Density Fluctuations
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Flow
https://arxiv.org/abs/2007.04682
Flow into planar obstacleReverse shock forms
B
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Planar shock experiment: Aluminium, stable
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Flow
https://arxiv.org/abs/2007.04682
Flow into planar obstacleReverse shock forms
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Planar shock experiment: Tungsten, Turbulent
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Flow
https://arxiv.org/abs/2007.04682
Flow into planar obstacle???? forms
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New Diagnostics: Imaging Refractometer
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New Diagnostics: Imaging Refractometer
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New Diagnostics: Imaging Refractometer
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Page 72
Ray d
eflection
angle (m
rad)
30
-30
Space
0
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Flow
Planar shock experiment: Tungsten, Turbulent
Flow
https://arxiv.org/abs/2007.04682
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Flow
Planar shock experiment: Tungsten, Turbulent
Space [email protected] PPPL 2020
Flow
https://arxiv.org/abs/2007.04682
Ray d
eflection
angle (m
rad)
30
-30
0
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Measuring the Spectrum of Deflection Angles
Undeflected raysDeflected rays
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Flow
0.8 0.6 0.4 0.2Intensity (a.u.)
Flow
https://arxiv.org/abs/2007.04682
Ray d
eflection
angle (m
rad)
30
-30
0
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Measuring the Spectrum of Deflection Angles
Undeflected raysDeflected rays
L
n
n
n
Ln
cr
e
cr
e
22
1
=
FWHM D β 0.75 degrees
Spatialscale
Deflectionangle
Need a theory to link distribution of total deflection angles to the spectrum of density fluctuations
Random walk -> Gaussian
[email protected] PPPL 2020
Flow
0.8 0.6 0.4 0.2Intensity (a.u.)
https://arxiv.org/abs/2007.04682
Ray d
eflection
angle (m
rad)
30
-30
0
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Measuring the Spectrum of Deflection Angles
Undeflected raysDeflected rays
L
n
n
n
Ln
cr
e
cr
e
22
1
=
FWHM D β 0.75 degrees
Spatialscale
Deflectionangle
Need a theory to link distribution of total deflection angles to the spectrum of density fluctuations
Random walk -> Gaussian
But - deflection spectrum notGaussian!
[email protected] PPPL 2020
Flow
0.8 0.6 0.4 0.2Intensity (a.u.)
https://arxiv.org/abs/2007.04682
Ray d
eflection
angle (m
rad)
30
-30
0
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Faraday Rotation Imaging: Out of Plane Magnetic Fields
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No axial fields in inflowsAxial interferometry
Out of planefields
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Local measurements from Thomson Scattering
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Ion Feature:Collective scattering, 28-points
Electron Feature:Collective and non-collective scattering
Probebeam
Bulk Flow,Electron and iontemperatures
Electron temperature,density
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Page 79
Outline
β’What is magnetic reconnection?
β’Reconnection and Diagnostics on the MAGPIE generator
β’Anomalous heating and the Plasmoid Instability
β’Creating turbulence through flux tube merging
β’Diagnostics for turbulence
β’ The PUFFIN facility
Pulsed Power Driven Reconnection, [email protected] 79
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Long drive times required to study instabilities and turbulence
[email protected] JPP 2020
Flux tube mergingPlasmoid Instability
5 mm
Wires
5 mm
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Pulsed Power Driven Reconnection, [email protected] 81
Emperor Penguin:
4 ft/1.2 m
1.5 MA peak current, 1.5 Β΅s rise time
[MAGPIE: 1.4 MA, 0.25 Β΅s]
Starting January 2021 at MIT
Instabilities and turbulence need time to develop.
Vacuum coaxtransmission lines
Vacuum chamber
PUFFIN: A long drive pulser for fundamental plasma physics
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Conclusions
β’ Reconnection and turbulence in collisional HED plasmas
β’ Sub-AlfvΓ©nic reconnection, anomalous heating, plasmoid unstable
β’ Magnetised turbulence with Pr < 1, π½ βΌ 1
β’ New diagnostics to study turbulence in unprecedented detail
β’ PUFFIN: a new long drive pulser for magnetised HED plasmas at MIT
[email protected] PPPL 2020 82