CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority Presentation on prioritisation of DIVSOL proposals for M9 Andrew Kirk

Andrew Kirk MAST team meeting 28/11/12 M9 Top Level Goals Understanding ELM control by RMPs Understanding pedestal stability using measured edge current and flows Test the ion-scale transport paradigm quantitatively Develop a MAST-U relevant scenario (low-li H- mode, no P3 coil) matched by a semi-empirical simulation Generate a mean-value and fluctuation SOL ne database to develop modelling tools for super-X Understanding fast-ion transport from visible modes to guide q(r) and beam source config

Andrew Kirk MAST team meeting 28/11/12 M9 proposals received 20 proposals received requesting 240 shots Following an internal review and PLF 2 proposals have been merged with others 10 priority 1 proposals remain with 114 shots allocated There are 4 priority 2 proposals that 40 potential extra shots would get time if the accompanying priority 1 proposal is successful

Andrew Kirk MAST team meeting 28/11/12 M9 proposals linked to top Level Goals

Andrew Kirk MAST team meeting 28/11/12 M9 proposals linked to MAST_U

Andrew Kirk MAST team meeting 28/11/12 Other P1 M9 proposals Linked to Phds/ basic science

Andrew Kirk MAST team meeting 28/11/12 M9 proposals – that could become P1 Shots that would fight for the contingency if previous shots are successful

Andrew Kirk MAST team meeting 28/11/12 SOL-001 Characterisation of SOL physics in L-mode Shots:24 Determining and understanding how the SOL responds to plasma and geometrical changes is crucial in order to predict its behaviour in long divertor configurations (MAST-U) or in the next generation tokamaks (ITER, DEMO). Recent theoretical models (Miltello PPCF 2012) provide a scaling of the SOL width as a function of the edge parameters, finding a direct dependence with respect to the density and inverse with respect to the plasma current and electron temperature. Experimental (Scarabosio et al. PSI 2012) Theoretical (Militello et al. PPCF, submitted Aug 2012) Similar trends are found in experimental results from conventional tokamaks although the scalings are based on engineering parameters Aim: Characterise the L-mode upstream SOL decay length in terms of local edge parameters

Andrew Kirk MAST team meeting 28/11/12 #IpBTNBI kA0.4T/ kA0.585T/ kA0.585T/ kA0.585T1 source SOL-001 Characterisation of SOL physics in L-mode Changes q and B Changes T and B or q Changes T Parameters to scan: density, temperature, magnetic field, q95, length of SOL Diagnose the edge plasma as completely as possible

Andrew Kirk MAST team meeting 28/11/12 SOL-002 Measurement of plasma potential fluctuations Measurements will be made with the adapted Gundestrup probe Plans to measure RMS potential profiles to investigate decay length and structure and compare with density, temperature Potential near the seperatrix to investigate difference between closed and open field line regions Fluctuation PDF of potential and density from which we can compare PDF moments against theory Shots:16

Andrew Kirk MAST team meeting 28/11/12 [Eich et al, IAEA 2012] NSTX Present assumption for ITER is q ~ 3 mm Measurements from a range of tokamaks suggest that the fall off length is much smaller than this: q ITER ~ 1 mm [Eich et al, PRL 107 (2011) ] Heat flux profiles are fitted using a fall off and diffusion term; –Convolution of a gaussian and an exponential profile MAST IR profiles are well fitted by this profile and fit the trend of other machines SOL-003 SOL fall off length measurements inter-ELM Shots:10

Andrew Kirk MAST team meeting 28/11/12 SOL001-3b Heavily Diagnosed Plasma Study Create low and high density reference shots –Ip = 600kA, 1 beam, L-mode double null –Magnetic feedback for RP measurements, optimise for divertor RFEA –Repeat to take data using IR, LPs, DivCam (D α, Carbon, Helium lines), coherence imaging, different BES positions –Repeat when different RP heads become available Specific Diagnostics: RP, DivCam, IR coverage of both divertors, BES position scan, coherence imaging, DSF RFEA Proposal combined with SOl001,2,3

Andrew Kirk MAST team meeting 28/11/12 Obtain complete target profiles during inter-ELM and ELMs combined with midplane measurements Obtain target and mid-plane ion temperature measurements in L-mode SOL-004 Ion temperature measurements Shots:20

Andrew Kirk MAST team meeting 28/11/12 SOL-005 Divertor impurity studies CII filtered light Initial experiments in low power shots Goal to inject into H-mode shots with significant parallel Temperature gradient Obtain flow data and C transport for comparison with modelling Shots:10

Andrew Kirk MAST team meeting 28/11/12 SOL-006 Identification of GAMs Aim: To verify that GAM-like oscillations are observed in the baseline scenario 1 discharge (21856) with Ip=400 kA, B0=0.52 T and q95=6 using active and passive diagnostics: reciprocating probe, EBW, Thomson scattering If successful would go on to determine its dependence on plasma parameters Numerical modeling with CENTORI code suggests a strong dependence of GAM properties on plasma parameters such as q95, ratio of ion and electron temperatures and plasma elongation. Shots:8

Andrew Kirk MAST team meeting 28/11/12 SOL-007 Fast heat pulse propagation in the divertor A time-dependent model for the influx of W from the ITER divertor during ELMs is being developed at the IO using the OSM-EIRENE- DIVIMP code package. Benchmarking is required of course, and MAST provides an opportunity for direct imaging of the heat pulse propagation via filtered high-speed camera imaging, specifically CII, CIII and He, which have well defined “ temperature emission bands ”. Shots:12

Andrew Kirk MAST team meeting 28/11/12 SOL-008 Benchmarking of coherence imaging Coherence Imaging (CI) is a powerful technique for 2D ion flow (and possibly T i ) imaging using Doppler spectroscopy of visible emission, and enables tomographic inversion to recover flows on an R-Z cross-section. It is already being used for passive flow measurements on DIII-D. A new CI diagnostic has been developed for MAST in a collaboration between Durham University, CCFE, Australian National University and York University, and will be installed for the first time for M9. Before experiments using this diagnostic, it is important to benchmark the instrument against an existing flow measurement to ensure we fully understand the output of this new system. This proposal is to benchmark CI against ECELESTE by simultaneously measuring outboard midplane He II flows with both diagnostics. Shots:7

Andrew Kirk MAST team meeting 28/11/12 SOL-009 Flow imaging in the divertor The new Coherence Imaging diagnostic with its wide-angle divertor view gives us the opportunity to image divertor flows of multiple species over the entire divertor cross-section. By measuring multiple species in repeated shots we can look at the behaviour of different charge/mass impurity flows and possibly extend the spatial coverage (due to different spatial distributions of the different ionisation states) Shots:7

Andrew Kirk MAST team meeting 28/11/12 SOL-010 NIR spectral survey Aim: To investigate the diagnostic potential of NIR ( nm) spectroscopy by collecting survey spectra for a variety of plasma conditions and to compare UV-VIS line and continuum emission to NIR spectra. Shots:0

Andrew Kirk MAST team meeting 28/11/12 Summary Most of the proposals (SOL-001-SOL—4) help us to meet the top level goal of Generate a mean-value and fluctuation SOL ne database to develop modelling tools for super-X As well as investigating diagnostics for MAST_U (SOL ) The remainder look at completing basic science studies (SOL- 005-SOL-006) and one is directly related to ITER (SOL-007)