The Australian Plasma Fusion Research Facility: Overview and Upgrade Plans(is there potential to be an additional training platform in diagnostics and plasma physics for KSTAR?)
B.D. Blackwell, J. Howard, D.G. Pretty, J.W. Read, H. Punzmann, J. Bertram, M.J. Hole, F. Detering, C.A. Nuhrenberg, M. McGann, R.L. Dewar, J. Bertram Australian National University, and *Max Planck IPP Greifswald,
Photo: Martin Conway
Australia-Korea Foundation mission to KSTAR, 2010
The Australian Plasma Fusion Facility: Results and Upgrade Plans
IntroductionResult Overview: MHD Modes in H-1
Data miningAlfvénic ScalingOptical MeasurementsRadial Structure
Facility Upgrade Aims Key areas New diagnostics for Upgrade
Conclusions/Future
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H-1NF: the Australian Plasma Fusion Research Facility
Originally a Major National Research Facility established by the Commonwealth of Australia and the Australian National
University
Mission:• Detailed understanding of the basic physics of magnetically
confined hot plasma in the HELIAC configuration• Development of advanced plasma measurement systems• Fundamental studies including turbulence and transport in plasma• Contribute to global research effort, maintain Australian
presence in the field of plasma fusion power
MoU’s for collaboration with
Members of the IEA implementing agreement on development of stellarator concept.
National Institute of Fusion Science, Princeton Plasma Physics Lab
Australian Nuclear Science and Technology Organisation
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H-1 CAD
4
Major radius 1mMinor radius 0.1-0.2mMagnetic Field 1 Tesla (0.2 DC) q 0.5 -1 (transform 1~2)
ne 1-3x1018
Te 20eV (helicon) <200eV (ECH) 0.01 - 0.1%
Blackwell, Australian ITER Workshop, 10/2006
H-1NF Photo
H-1 configuration (shape) is very flexible
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• “flexible heliac” : helical winding, with helicity matching the plasma, 2:1 range of twist/turn
• H-1NF can control 2 out of 3 oftransform ()magnetic well andshear (spatial rate of change)
• Reversed Shear like Advanced Tokamak mode of operation
Edge Centre
low shear
medium shear
= 4/3
= 5/4
twis
t pe
r tu
rn (
tran
sfor
m)
Blackwell, Australian ITER Workshop, 10/2006
Large Device Physics on H-1Confinement Transitions,
Turbulence (Shats… 1996--)– H-mode 1996
– Zonal Flows 2001
– Spectral condensation of turbulence 2005
Magnetic Island Studies – H-1 has flexible, controlled and verified geometry
– Create islands in desired locations (shear, transform)
– Langmuir probes can map in detail
Alfvén Eigenmodes (next )
D3D tokamak H-1
Pinj (MW)
1
2
3
Edge ne (1019 m–3)10
Edge Te (keV)
0.1
0.2
0.3
1600 2000 2400 2800t (ms)
Edge Te (eV)
t (ms)
6
3
Prf (kW)
ne (r/a = 0.3) (1017 m–3)
80
40
0
030
20
10
20 40 60
Experimental confirmation of configurationsRotating wire array• 64 Mo wires (200um)• 90 - 1440 angles
High accuracy (0.5mm)Moderate image quality Always available
Excellent agreement with computation
T.A. Santhosh Kumar B.D.Blackwell, J.Howard
Santhosh Kumar
Iota ~ 1.4 (7/5)
Effect of Islands on Plasma• LHD, JT60U results show
– Te profile flattened – radial transport high
(inside side to outside side)– But this doesn’t mean that internal transport is high
(from the inside to the outside of the island.)– Internal rotational transform is quite low and can complicate experiments– 10 to 100 toroidal transits to circumnavigate island?
Conditions:
Argon plasma ~10eV
Te ~ 10 eV, Ti ~ 10 eV 30-80 eV∼
electron density 1 × 10∼ 18/m3
nn < neutral fill density 0.81 × ∼ 1018/m3
ρe 0.075 mm, ρ∼ i 35-55 mm∼
νei 9×10∼ 5/sec νen 1.6×10∼ 5/sec
Collision mean free path λei 2.5 m, λ∼ en 8 m∼
Santhosh Kumar
Small, core islands
Density peaked near island axis (O-point)
Potential negatively peaked there too.
Local symmetry about local magnetic axis, but apparently not globally (axis to axis)
Blackwell, Kyoto JOB 16th March 2009
B AC
Unanswered QuestionsIssues Remaining:
What is the correct analysis for Er?When does the plasma “see/not see” islands”
collisionality, i, e internal transform are important
What is the most robust indicator of surface number?
(p? – varies with ne by a fraction of Te (Boltzmann relation))
“Correct” analysis for Er?If we take the axis at the core core electron rootIf we assume two axes, then ion root, but field is
still large (characteristic of e-root)[Conditions for usual e-root picture (1/, trapped e) not met]
MHD/Mirnov fluctuations in H-1
Blackwell, ISHW Princeton 2009 13
David Pretty
Identification of Alfvén Eigenmodes: ne• Coherent mode near iota = 1.4, 26-60kHz,
Alfvénic scaling with ne• m number resolved by bean array of Mirnov
coils to be 2 or 3.
• VAlfvén = B/(o) B/ne
• Scaling in ne in time (right) andover various discharges (below)
phase
1/ne
ne
f 1/ne
Critical issue in fusion reactors:
D + T He + n
VAlfvén ~ fusion alpha velocity fusion driven instability!
Blackwell, KSTAR2010
Identification with Alfvén eigenmodes: k||, iota
Why is f so low? - VAlfven~ 5x106 m/s
res = k|| VA = (m/R0)( - n/m) B/(o)
• k|| varies as the angle between magnetic field lines and the wave vector
k|| - n/m
• iota resonant means k||, 0
Expect Fres to scale with iota
ota (twist)
= 4/3
Resonant
Mode structure via synchronous 2D imaging• Intensified Princeton Instruments camera synchronised with mode
• Light imaged for various delays
• Averaging/Accumulation is performed by the camera
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Toroidal Field Coils
HelicalConductor
John Howard, Jesse Read
Alfvén Eigenmode structure in H-1Compare cylindrical mode with optical emission
measurementsTest functions for development of a Bayesian
method to fit CAS3D modes to experiment.
John Howard, Jason Bertram, Matthew Hole
First Results from Gas Puff Imaging - true 2D imaging
• Intensified Princeton Instruments camera synchronised with mode
• Select a small range of toroidal angles with a gas puff (Neon)
• Intensity ~ ne
• Initial results 2D image without assumptions of rotation, mode number.
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John Howard, Jesse Read
Mirnov Array 1
Mirnov Array 2
Interferometer
RF Antenna
Viewline
Gas Puff
Third Mirnov Array (Toroidal)
New Toroidal ArrayCoils inside a SS thin-wall bellows (LP, E-static shield)
Access to otherwise inaccessible region with•largest signals and •with significant variation in toroidal curvature.
Shaun Haskey
Mirnov Array 1Mirnov Array 220 pickup coils
Interferometer
RF Antenna
0.2m
Australian Plasma Fusion Research Facility Upgrade
2009 Australian Budget Papers
• Australian Government’s “Super Science Package”
• Boosted National Collaborative Infrastructure Program using the “Educational Infrastructure Fund”
$7M, over 4 years for infrastructure upgrades (no additional funding for research)
Aims of Facility Upgrade
Consolidate Facility infrastructure including that required to implement the Australian ITER Forum strategy plan
Aim to involve the full spectrum of the ITER Forum activities
More specifically:• Improve plasma production/reliability/cleanliness
– RF production/heating, ECH heating, baking, gettering, discharge cleaning
• Improve diagnostics– Dedicated density interferometers and selected spectral monitors
permanently in operation
• Increasing opportunities for collaboration– Ideas?
• Increasing suitability as a testbed for ITER diagnostics– Access to Divertor – like geometry, island divertor geometry
RF Upgrade
RF (7MHz) will be the “workhorse”– Low temperature, density limited by power– Required to initiate electron cyclotron plasmaNew system doubles power: 2x100kW systems.New movable shielded antenna to complement “bare” antenna
(water and gas cooled).Advantages:– (non resonant – Helicon) Very wide range of magnetic fields in Argon – (ion-cyclotron resonant) New system allows magnetic field scan while
keeping the resonant layer position constant.e.g. to test Alfven scaling MHD
Additional ECH source (10/30kW 14/28GHz) for higher Te
Improved Impurity Control
Impurities limit plasma temperature (C, O, Fe, Cu)High temperature (>~100eV) desirable to excite spectral lines
relevant to edge plasma and divertors in larger devices.
Strategy : Combine - • Glow discharge cleaning for bulk of tank• Pulsed RF discharge cleaning for
plasma facing components.• antenna (cooled) and source (2.4GHz)
• Low temperature (90C) baking • Gettering – Titanium or Boron (o-carborane)
Access Island Divertor Geometry
Ashley Gibson
“Island Divertor”
Small Linear Satellite Device – Plasma Wall Interaction Diagnostics
Purpose:Testing various plasma wall interaction diagnostic conceptse.g. Doppler spectroscopy, laser interferometry
coherence imaging, imaging erosion monitor
Features:Much higher power density than H-1 H-1 cleanliness not compromised by material erosion diagnostic testsSimple geometry, good for shorter-term students, simpler projectsShares heating and magnet supplies from H-1
Magnetic Mirror/Helicon chamber
Mirror coils
Optical Diagnostics
Heliconsource
ne ~ 1019 m-3
P ~ 1MW/m2
Helicon H+ source ConceptBased on ANU, ORNL work
Quartz/ceramic tubem=+1 Helicon AntennaDirectional
Gas Flow
• Helicon Antenna is an efficient plasma source in Ar• High Density (>1018 m-3) more difficult in H• Combination of higher power and non-uniform
magnetic field has produced ne ~ 1019 m-3in H
Water cooled target
Mirror Coils
ne ~ 1019 m-3
(Mirror coils at one end should be sufficient – mainly to provide field gradient rather than full mirror effect.)
Additional Power/Plasma Sources
Sheath acceleration increases power density, but if >30-50V physical sputtering
(not normal in fusion simulators, but may be useful to increase erosion?)
E-beam can increase dissipation, but ion bombardment damage of LaB6 cathode if pressure too high?Solid LaB6 Cathode, >10A emission
Sterling Scientific washer gun H+ 1019-1020
5-15eVunder the right conditions, can generatea relatively clean plasma (low W)den Hartog: Plasma Sources Sci. Technol. 6 (1997) 492–498.
(also useful for a simple way of obtainingfirst plasma)
15mm
Future
Research • New Toroidal Mirnov Array • Bayesian MHD Mode Analysis• Toroidal visible light imaging (Neon)• Correlation of multiple visible light, Mirnov and n~
e data• Spatial and Hybrid Spatial/Temporal Coherence Imaging
Facility upgrade• Develop divertor and edge diagnostics• Study stellarator divertors, baffles
e.g. 6/5 island divertor• Develop “plasma wall interaction” diagnostics • Linear “Satellite” device for materials diagnostic development
multiple plasma sources, approach ITER edge
Blackwell, H1 Results & Upgrade, AKF_KSTAR 2010
H-1NF is an excellent toroidal graduate student machine – complements Korean facilities
• Large device physics accessible – MHD/Alfvénic modes.– Island studies
• Very good diagnostic access – Invites imaging and multiview interferometric diagnostics
• Precise control of magnetic geometry, q (0.5 1) and shear.• High repetition rate, availability
– 0.5 Tesla : 200 shots/day (hydrogen/helium/deuterium)– Low field student mode : 500 shots/day (argon, Langmuir probes etc.)
• Complementary high density hydrogen linear machine (~1019)– Simpler geometry– Edge plasma density and power density approaching ITER (over a small area)– fast diagnostic/vacuum “turnaround” time
• MDSPlus/JavaScope data common between KSTAR/H-1NF/MDFBlackwell, H1 Results & Upgrade, AKF_KSTAR 2010