Transport and Confinement: proposals for M9

1. Transport and Confinement:proposals for M9 M Valovič for T&C team MAST Team Meeting 28 Nov 2012

2. Long term objectives for T&C 2.iii Understand fuelling and impurity transport for JET D-T, ITER and CTF (e.g. including RMP effects) control of density at acceptable burnup fraction 3.i Analyse edge and SOL conditions during L-H transition and test predictive model. control of L-H transition 2.ii Determine dependencies of heat transport on key parameters for extrapolation to CTF and ITER (including rotation, MHD, ion species) by integrated experiment and modelling 2.i Characterise turbulence fluctuations in MAST and compare with models extrapolation towards low n*, low q, high b

3. M9 Transport & Confinement proposals

4. TC-014: Measure perturbative particle transport in MAST • Background • Particle transport in STs is not well understood • important for predicting density profile and bootstrap current. • established technique, tried on MAST • New is a combination with BES to check D, V~const during modulation. • Aim • Long-pulse, MHD-quiescent L-mode • gas puff synchronized with Thomson • Scans: • Bt, Ip, RMP, L v.s. H-mode • compare neoclassical and gyrokinetic calculations • Team • Ren, Guttenfelder, Kaye (all PPPL), Field, Garzotti G -n

5. TC-001: Impurity transport studies Background Previous C and He data indicate q-dependent pinch But data incomplete: L-mode methane q-scan not dimensionless (1beam), difficult to compare with theory, i.e. parallel compression pinch H-mode high-q He and low-q C data needed to confirm neoclassical transport Viewing lower ionisation states needed to provide a further constraint in the fit of D and V Use of N (extrinsic) will help confirm C results and with He gives Z scan Aim Complete scans with C and He Repeat scan with: N (CX 566.9nm) MSE, FIDA [Ne (CX 524.9nm, r/a < 0.5)] Modelling: SANCO, UTC, GS2 Team Henderson (PhD), Garzotti, Crowley, Patel, Valovic, Roach and others

6. TC-002: Pellet fuelling of plasma with ELMs mitigated by RMP • Background • ITER assumes no interaction between pellet fuelling and RMP ELM mitigation • favourable example found on MAST but not diagnosed • Aim • Document favourable case • Understand the difference between favourable and unfavourable cases • Reduce gas, better RMP, DND • Background data: • why weak inward diffusion of pellet material ? • pellet deposition, pellet spectroscopy, striations, drift, poloidal asymmetry, BES • Team • NIFS collaboration • Valovic, Garzotti, Gurl, Kirk, Naylor, Koechl (Austria), Field,… RMP

7. TC-008: Effect of fuelling on H-mode access • Background • During the M8 PL-H ~ 2.5 MW but discharge with different fuelling location had PL-H < 1 MW. • Aim • Determine whether the cause of the low PL-H is fuelling location: • Repeat low PL-H plasma and measure PL-H • Change from mid-HFS to top/bottom HFS and measure PL-H. • Measure edge profiles during power scans. • If no difference change the shape • Team • H Meyer, J Hillesheim, A Patel, R Scannell

8. TC-006: Dependence of H-mode access on Ip • Background • CTF is designed to operate at high Ip/B • Conventional PL-H scaling is Ip - independent. • PL-H ~ Ip is observed on NSTX and AUG (low density ECRH). • Indication that ion orbit loss and grad Er plays the role • Aim • Test the grad Er hypothesis (in comparison with XGC0 code) • Power scans at : • Ip = 0.5 MA and 1 MA at Bt =const • 2 Ip values at q =const. • low and high density • Characterise the evolution of edge Er, Te, ne, Ti through the L-H transition. • Repeat discharges close to L-H threshold to measure fast vHeII. • Team • Meyer, Hillesheim, Patel

9. TC-007: Characterisation of I-phase • Background • I-Phases (dithery H-mode) are attributed to the interplay between the predator (flow) and the prey (turbulence) • MAST data seems to differ from this model: no phase shift between flow and turbulence. • Aim • Determine the interplay between flow, turbulence and profiles in I-phase • In addition to ECELESTE add: SAMI, DBS, BES, Mach probe • Team • Hendrik Meyer, Jon Hillesheim, Ash Patel, Vladimir Shevchenko, Geoff Cunningham, Simon Freethy, Anthony Field

10. TC-005: Compare flow measurements by ECELESTE and SAMI • Background • Synthetic Aperture Microwave Imaging system used as Doppler reflectometer can measure speed of density fluctuations at the edge • How this relates to the velocity of helium from ECELESTE? • Aim • Search for correlations between SAMI and ECELESTE • On existing shot adjust the outer radius so that RECELESTE =RSAMI • Use single frequency SAMI for maximum temporal resolution. • Use combination of frequencies for radial resolution • Team • V Shevchenko, H Meyer, S Freehy, R. Vann

11. TC-009: Collisionality dependence of ion scale turbulence • Background • In L-modes transport is found n* independ • But in MAST, BES data are interpreted as inverse linear dependence of zonal flow amplitude on collisionality - inconsistent with n* scaling if ZF controls turbulence • Aim • realise dimensionless n* scan in L-mode • Document heat transport and density fluctuation data from BES • GS2, NEORB modelling • Team • A Field, M Fox, M Valovic, O Jones, B Crowley, Roach, … Luce ~1/jZF Y-C Kim et al.

12. TC-010: Influence of flow shear on low-k turbulence YC Kim, et al • Background • Ion heat transport is controlled by flow shear (ITER, CTF) but effect is not fully quantified (shift or stiffness ?) • In MAST favourable effect of toroidal flow shear on grad(Ti) found in (mostly L-mode) dataset • But: • u’/vith is correlated with power • BES dataset incomplete • Aim • Study the influence of actively changing toroidal flow shear on ion-scale turbulence • Plasma: SND L-mode, breaking by RMPs (n=4) • Scans: • BES (3 shots per condition) • RMP current (0.7, 1.0, 1.3 kA) • Diagnostics: CXRS, BES, DBS, other transport diagnostics • Modelling: GS2, NEORB • Team • Field, Fox (PhD), Guttenfelder, Hillesheim, Valovic, Kirk, Roach, .. ~u’/vi,th

13. TC-013: Influence of q-profile on flow shear effects • Background • CTF is designed with Ip because of favourable scaling. • However in (L-mode) GK theory shows: • flux at the edge is smaller than measured with shortfall zone becoming smaller with decreasing q • eddy tilt larger than measured • Hypothesis: • q/e is proportional to u||/u which controls the turbulence, and GYRO underestimates shear flow term. • Aim • Test this hypothesis using dedicated L-mode q-scan • Start with simple q scan varying Ip with Bt, P=const; measure BES (3 shots/q) • If time perform dimensionless q scan (power match) • Diagnostics: CXRS, BES, DBS, other transport diagnostics • Modelling: Transport, GYRO simulations. • Team • Hillesheim, Field, Fox (PhD), Valovic

14. TC-004: Transport towards low collisionality • Background • Collisionality is the largest extrapolation variable to CTF • In H-modestrong favourable dependence so far- location of saturation point is critical • Aim • Extend scan towards lower n* in H-mode by higher PNBI (25%) and BT (8%) • document the electron heat transport at low n*; search for saturation • Diagnostics: BES, FIDA signals • Modelling: nonlinear GS2 codes in particular micro-tearing and ETG modes • Team • Valovic, Field, Garzotti, Crowley, Jones, Akers, Colyer, Roach, Dickinson, …

15. TC-012: Improve beta scan of heat transport in H-mode • Background • 2nd largest extrapolation towards CTF is b • Attempted in M8 but scan is challenging: carbon accumulation at the edge • Aim • Reduce carbon accumulation by ELMs (RMP, kicks, z-shifts) • Diagnostics: FIDA and BES • Modelling: GS2 for role of MTMs, KBMs, ETG • Team • Valovic, Garzotti, Kirk, Jones, Field, Crowley, Akers, Scannell, Guttenfelder, Dickinson, Newton, Roach, Colyer, Newton,…

16. TC-003 Parametric dependence of electron heat transport • Background • In MAST H-modes electron transport dominates • Understanding could be improved by actively probing parametric dependencies of electron heat flux on accessible parameters: qe = f (LTe, s, u’, …) • Aim • Establish robust H-mode (with help of ISD) • measure sensitivity of qe on: • LTe, profile stiffness (power scan) • q and s (q scan) • toroidal velocity shear (RMP) • Diagnostics: BES (i.e. microtearing), FIDA for constraining fast ion transport • Modelling: GS2 role of MTM or ETG • Team • Valovic, Garzotti, Jones, Field, Crowley, Akers, Scannell, Dickinson, Newton, Roach, Colyer, …

17. TC-011: Momentum transport core periphery Time [s] • Background • Momentum transport is an issue for ITER and CTF; affects MHD and transport • Methodology similar to particle transport • Aim • Aims to separate diffusivity and pinch from the flux – u’F dependence. • Modulate momentum flux by: • 20ms NBI modulation (done in M7) • Switching-off RMP, n=4, SND plasma • Determine ,V from CXRS • Monitor BES, DBS and check ,V =const, compare with GS2 and GYRO • Team • Guttenfelder, Ren, Kaye (PPPL), Field, Kirk, Crowley, Hillesheim, …

18. Backup and cross-areas T&C proposals • Dependence of H-mode access on X-point height • Species dependence of L-H threshold • Effect of RMP on L-H threshold and first ELM • Pellet v.s. gas fuelling of H-mode • Comparison of pellet deposition with LFS and VHFS launch