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 Facility The Upgrade ( ) Result Overview: H-1NF Data mining Alfvénic Scaling Optical Measurements Radial Structure MDF Results Aims Key areas New diagnostics for Upgrade Conclusions/Future 2

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 of Japan, Princeton Plasma Physics Lab Australian Nuclear Science and Technology Organisation 3

H-1 CAD 4 Major radius1m Minor radius m Magnetic Field  1 Tesla (0.2 DC) q (transform 1~2) n e 1-3x10 18 T e 20eV (helicon) <200eV (ECH)  %

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 upgrades RF heatingvacuum and power systems, diagnosticscontrol 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

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Overview of H-1 results

H-1 configuration is very flexible 11 “flexible heliac” : helical winding, with helicity matching the plasma,  2:1 range of twist/turn H-1NF can control 2 out of 3 of transform (  ) magnetic well and shear  ( 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 (transform)

MHD/Mirnov fluctuations in H-1 Blackwell, ISHW Princeton

Three Mirnov Arrays (Toroidal) New Toroidal Array Coils 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 David Pretty Mirnov Array 1 Mirnov Array 2 20 pickup coils Interferometer RF Antenna 0.2m

Flucstruc analysis via SVD  phase vs  Chronos Singular Values Topos PSD of chronos Time (ms) Singular vectors are grouped by similarity to separate simultaneous modes Follows plasma shape, amplitude variation is much less Helical Array resolves n and m, but not independently e.g. 9/7,8/7,7/6 sim.

zero shear rational surfaces Phase Clustering Separates Modes Observed frequency K || after correction for  n e Spread decreases Clusters lies close to k || cyl. for expected n,m apart from a factor of ~3 (iotabar taken along solid line) kHz k || (rad/m) f (kHz) Shaun Haskey David Pretty

Mode Physics?  res = k || V Alfvén = 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 physics Alfvén ~5e6 m/s – in principle, ICRH accelerates H+ ions but poor confinement of H+ at V A (~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 Bertram Matthew Hole Carolin Nuhrenberg

Scaling discrepancies  res = k || V Alfvén = k || B /  (  o  ) Numerical factor of ~ 1/3 required for quantitative agreement near resonance – Impurities (increased effective mass) may account for 15-20% – 3D MHD effects ~ 10-30% (CAS3D), still a factor of 1/1.5-2x required Magnetic field scaling is unclear Unknown drive physics – Alfvén ~5e6 m/s – in principle, H+ ions are accelerated by ICRH, but poor confinement of H+ at V A (~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?) 18

Optical Imaging of Internal Mode Structure Intensity  proxy for n e 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 eBeams Field lines from accurate magnetic model (red) are matched with ebeam images (black) John Howard Nandika Thapar Jesse Read

J. Howard: Synchronous Imaging of MHD Modes in H-1 J. Howard, J. Read, J. Bertram, B. Blackwell Howard, 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-1 Raw 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:  I / I Supersonic nozzle (Ne injection) John Howard Jesse 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  10 19/m3 3eV (Power density destroys probes above this) H  10 18/m3 (first tests~1kW) 5kW available, 20kW (2013) dynamic tuning (100us) tried for Ar + blue core Ar 200W T e Ar – 1400Wn i Ar W n i H 1200W H Visible Spectra Ar low pwr Ar “blue core” Ar HH HH Cormac Corr Juan 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 Composite images of the brightness, azimuthal flow speed and argon ion temperature in the magnetic mirror region of the MDF device (3.0 mTorr) antenna target region John Howard Romana 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 n e to increase axially  5mm Juan Caneses Lei Chang

Modelling with the UT/ORNL codes Radial wave profiles in reasonable agreement – usually requires ~10  ei Further work required matching n e profiles in (r,z) with experiment Lei Chang Juan Caneses

Future Research 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

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