Recent results from the Australian Plasma Fusion Research Facility

B. D. Blackwell, J. Howard, D.G. Pretty, S. Haskey, J. Caneses, C. Corr, L. Chang, N. Thapar, J.W. Read,

J. Bertram, B. Seiwald, C.A. Nuhrenberg, H. Punzmann, M. J. Hole, M. McGann, R.L. Dewar, F.J. Glass, J. Wach,

M. Gwynneth, M. Blacksell

The Australian Plasma Fusion Facility: Results and Upgrade Plans

The FacilityThe Upgrade (2010-2013) Result Overview: H-1NF

Data miningAlfvénic ScalingOptical MeasurementsRadial Structure

MDF Results Aims Key areas New diagnostics for Upgrade

Conclusions/Future

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H-1NF: the Australian Plasma Fusion Research FacilityOriginally 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 of Japan, Princeton Plasma Physics LabAustralian 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%

The 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 upgradesRF heating vacuum and power systems, diagnostics control data access

(no additional funding for research)

Thomson 2 x 200kW 4-20MHz RF System

New cooled RF Antenna – helicon/ICRF

Antenna contoured to plasma shape

Insulators/Vacuum feed through

Tuning box

Diagnostic and Control Upgrades

Coherence Imaging Camera

Synchronous Imaging

Multichannel Interferometer

MDF Imaging

Screenshot of web browser at http://h1ds.anu.edu.au/mdsplus/H1DATA/58063/TOP/OPERATIONS/MIRNOV/A14_14/INPUT_2/

Screenshot of web browser at http://h1ds.anu.edu.au/mdsplus/H1DATA/58063/TOP/OPERATIONS/MIRNOV/A14_14/INPUT_2

Powerful web-based data browser • Low bandwidth required, open source• Full data resolution accessible• Same access for binary xml csv forms

firewall issues viewer software

Overview of H-1 results

H-1 configuration 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

twist

per

turn

(tra

nsfo

rm)

MHD/Mirnov fluctuations in H-1

Blackwell, ISHW Princeton 2009 12

Three Mirnov Arrays (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 HaskeyDavid Pretty

Mirnov Array 1Mirnov Array 220 pickup coils

Interferometer

RF Antenna

0.2m

Flucstruc analysis via SVD phase vs

Chronos

SingularValues

ToposPSD of chronos

Time (ms)

Singular vectors are grouped by similarity to separate simultaneous modesFollows plasma shape, amplitude variation is much lessHelical Array resolves n and m, but not independently e.g. 9/7,8/7,7/6 sim.

zero shearrational surfaces

Phase Clustering Separates Modes

Observedfrequency

K|| after correctionfor ne

Spread decreases

Clusters lies close to k|| cyl. for expected n,m apart from a factor of ~3(iotabar taken along solid line)

0

50

100k

Hz0

0.

1

k||

(rad/m)

f (kHz)

Shaun HaskeyDavid Pretty

Mode Physics?res = k|| VAlfvén = k||

B/(o)

Numerical factor of ~ 1/3 required for quantitative agreement near resonance

– Impurities (increased effective mass) may account for 15-20%

Density fluctuations acoustic?

As k|| 0, the mode is expected to become more “sound-like”

b~ll increases as 0

b~ perp

b~ parallel

b~ perp

Unclear drive physicsAlfvén ~5e6 m/s – in principle, ICRH accelerates H+ ions but poor confinement of H+ at VA (~40keV) makes this unlikely.

More complete analysis of orbits with H-1 parameters (Nazikian PoP 2008) reduces required ion energy considerably

H+ bounce frequency of mirror trapped H+ is correct order?

Electron energies are a better match, but the coupling is weaker. (mechanism?)

CAS3D Studies• Bumpiness (mirror) term in H-1 field requires hundreds of Fourier

components to represent parallel displacement.• This gives rise to a dense sound mode population in the range of

interest (0-100kHz) – which interact with the shear modes.• There are global modes here due to the finite beta gap (BAE)• Such modes can exhibit a similar but weaker frequency dependence

as our “whale tails” if the temperature profile is very hollow.

Can be resolved by: B scan or polarization study

Jason BertramMatthew Hole

Carolin Nuhrenberg

Optical Imaging of Internal Mode Structure

• Intensity proxy for ne

• CCD camera captures vertical view of plasma light, synchronised with the Mirnov signals, averaged over many cycles.

Phase locked loop waveforms

Calibrating View Geometry with eBeamsField lines from accurate magnetic model (red) are

matched with ebeam images (black)

John HowardNandika Thapar

Jesse Read

J. Howard: Synchronous Imaging of MHD Modes in H-1

J. Howard, J. Read, J. Bertram , B. BlackwellHoward, APFRF Facility and MDF – ANSTO 2010

Vertical view of plasma light synchronised with the Mirnov signals and averaged over many cycles.

Left: Intensity profile at the cross-section of the dashed line

Right: CAS-3D MHD code prediction of electron density.

Synchronous imaging

configuration scan

Poloidal mode structure agrees with magnetic data on both sides of both 5/4 and 4/3 resonances

Mode appears to be located at outer minor radii

HeI 668

Doppler Coherence Imaging on H-1Raw spatial heterodyne image (0.1T Argon)

Interference fringes encode:• velocity phase (shift) • temperature contrast

Results:• Ion temperature is hollow (10-25eV)• Rigid rotation of +/- 3km/sec at outer radii • Reflections from TF coils some degradation

Gas Puff Imaging of coherent fluctuations in H-1

View of plasma through H-1 porthole Movie of plasma oscillation showing an Alfvénic MHD mode

GPI:

dI / I

Supersonic nozzle(Ne injection)

John HowardJesse Read

Materials Diagnostic Test Facility• Explore effects of plasma on

advanced refractory materials• Joint ANU-ANSTO + USyd, UNew.++• Directly related to Gen 4 nuclear,

high temperature coal, solar• Uses H-1 power systems, diagnostics

MDF Prototype operational in new lab

Conditions approaching edge of Fusion reactor

MDF Plasma Parameters (low power)Argon 1019/m3 3eV (Power density destroys probes above this)H 1018/m3 (first tests~1kW) 5kW available, 20kW

(2013) dynamic tuning (100us) tried for Ar+ blue

core

Ar 200W

Te Ar – 1400Wni Ar - 1400W

ni H 1200W

H

Visible Spectra

Ar low pwr

Ar “blue core”Ar+ 440-488

Ha

H

Cormac CorrJuan Caneses

Cameron Samuel

Doppler Coherence Imaging of the MDF helicon source

3mT Argon in MDF: Composite images of brightness and azimuthal flow speeds

•Follows field lines• ~rigid rotation 1km/s•Ti <1eV on axis, rising at the edge

antenna target region

John HowardRomana Lester

Helicon waves in MDF• m = +1 circularly polarised wave as expected (k|| hard to match - below)• Attenuation lengths of 8cm – 24cm (in Ar)• Amplitude measurements and simulations indicate power is transported

to target by parallel flows rather than wave propagation.• Density increase less than expected for flux conservation (esp. in Ar)

K|| match requires ne to increase axially

5mm

Juan CanesesLei Chang

Modelling with the UT/ORNL codes

Radial wave profiles in reasonable agreement – usually requires ~10ei

Further work required matching ne profiles in (r,z) with experiment

Lei ChangJuan Caneses

FutureResearch • Use all 3 axes of the Toroidal Mirnov Array polarisation• Bayesian MHD Mode Analysis• Toroidal visible light imaging (Neon, He)• Correlation of multiple visible light, Mirnov and n~

e data• Spatial and Hybrid Spatial/Temporal Coherence Imaging• Island, chaotic and open field line physics• Plasma Surface Interaction physics

Facility upgrade• Improve facilities for developing divertor and edge diagnostics• Study stellarator islands, divertors, baffles

e.g. 6/5 island divertor• Develop “plasma wall interaction” diagnostics • Increase Power /Field on Materials Diagnostic Facility (H-1 power sys)

• multiple plasma sources, approach ITER edge