Tuomas Tala 1/16 ITPA TC Meeting, Princeton, USA 5 October – 7 October 2009 T. Tala (JET, DIII-D), W. Solomon (DIII-D, JET, NSTX) and S. Kaye, L.F. Delgado- Aparicio (NSTX) + large local teams in each tokamak not listed here 1 Association EURATOM-Tekes, VTT, P.O. Box 1000, FIN VTT, Finland 2 PPPL, Princeton University, Princeton, NJ USA ITPA TC-15, Dependence of Momentum and Particle Pinch on Collisionality

Tuomas Tala 2/16 ITPA TC Meeting, Princeton, USA 5 October – 7 October 2009 Status of TC-15 Joint Experiment: Dependence of Momentum and Particle Pinch on Collisionality Colour codes: XXX No progress (to my knowledge) XXX Some data exist, but not directly linked to this Joint Experiment XXX Experiment planned XXX Experiment done DeviceMomentumParticlePeriodLocal Key Person JET, 13 August, but …XXX/XXX 2009T. Tala DIII-D, 20 MayXXX 2009W. Solomon NSTX, AugustXXX 2009S. Kaye JT-60UXXX 2009M. Yoshida C-MODXXX 2009J. Rice / J. Hughes TCVXXX 2009H. Weisen

Tuomas Tala 3/16 ITPA TC Meeting, Princeton, USA 5 October – 7 October 2009 Motivation of Experiments collisionality,  Quantifying the parametric dependence of the momentum and particle pinch on collisionality, R/L n, q, T e /T i, β, … consolidates the extrapolation of both the toroidal rotation and density profiles for ITER Torque from ASCOT T i (and χ i ) from GLF23 v pinch  -2m/s v pinch  -5m/s v pinch  0 v pinch  -7m/s Dependence of ITER NBI Driven Rotation on v pinch Particle pinch determines density peaking on ITER C. Angioni, ITPA spring 2009 meeting T. Tala, IAEA 2008

Tuomas Tala 4/16 ITPA TC Meeting, Princeton, USA 5 October – 7 October 2009 Parameter Scans on DIII-D  Reference target plasma: low density, low NBI power 6MW (L-H power threshold was around 5.5MW, not 7MW as we had assumed), L-mode, no ECRH, T e /T i =1, low current (I p ~1MA), B t =2.0T  Collisionality: –finished successfully, 3-point scan for momentum, 2-point scan for n e –Traditional collisionality scan keeps density constant and varies temperature  R/L n : –Use pellets to decouple R/L n from collisionality (pellets very reliable and this scan was finished)  q: –Scan from lower I p =0.5MA to higher I p =2.0MA plasma, q- scan of density modulation missing

Tuomas Tala 5/16 ITPA TC Meeting, Princeton, USA 5 October – 7 October 2009 Successful Collisionality Scan (keeping  *, β, q constant) β IpIp nene TeTe TiTi v tor BtBt

Tuomas Tala 6/16 ITPA TC Meeting, Princeton, USA 5 October – 7 October 2009 Successful Collisionality Scan: scaled T e matched very well outside  >

Tuomas Tala 7/16 ITPA TC Meeting, Princeton, USA 5 October – 7 October 2009 Successful Collisionality Scan: n e matched as well as possible

Tuomas Tala 8/16 ITPA TC Meeting, Princeton, USA 5 October – 7 October 2009 Density Modulation Data Good Using the New Profile Reflectometer Time (ms) n e (10 19 m -3 )

Tuomas Tala 9/16 ITPA TC Meeting, Princeton, USA 5 October – 7 October 2009 Also Good Fluctuation Data from Reflectometer and BES

Tuomas Tala 10/16 ITPA TC Meeting, Princeton, USA 5 October – 7 October 2009 Different Experimental Technique on NSTX Aims (still the same): – Compare dependence of momentum pinch velocity on collisionality with analytic theory and/or gyrokinetic predictions – Compare momentum pinch velocity with particle pinch velocity Technique: – Use n=3 non-resonant magnetic perturbations to distort the rotation profile, allowing for separation of the roles of momentum diffusion vs convection (pinch). – Scan collisionality by varying I p and B t at fixed q (as reported by Kaye et al, IAEA 2006) – Use n e puffing and/or supersonic gas injection to perturb edge density and measure particle transport properties

Tuomas Tala 11/16 ITPA TC Meeting, Princeton, USA 5 October – 7 October 2009 Collisionality Scans at Fixed q Were Successfully Completed on NSTX  Obtained data for both momentum and particle pinch  Achieved approximately factor of two variation in collisionality

Tuomas Tala 12/16 ITPA TC Meeting, Princeton, USA 5 October – 7 October 2009 Dimensionless Scaling of T e and n e Shows Reasonable Matches during the Scan Obtained density profiles kept relatively fixed during the scan, also the scaled temperature profiles fairly similar between the shots

Tuomas Tala 13/16 ITPA TC Meeting, Princeton, USA 5 October – 7 October 2009 Inferred Pinch Velocity Shows a Collisionality Dependence, but … Aspects that can influence the momentum pinch: – Recoil pinch from particle flux – Nature of microturbulence (ITG vs TEM) – Trapped electron collisionality regime (collisionless versus collisional etc) Values of the pinch number Rv  / χ  roughly between -10 and 5

Tuomas Tala 14/16 ITPA TC Meeting, Princeton, USA 5 October – 7 October 2009 Magnetic Braking Appears to Slow Penetration of Impurities or Perhaps Even Expel Them  No Ne puff on these discharges.  Are we changing/introducing V pinch >0?  Can this effect at “mid-radius” be explained neo-classically?  Get D and V from time-dependent MIST modeling. No braking With braking

Tuomas Tala 15/16 ITPA TC Meeting, Princeton, USA 5 October – 7 October 2009 JET Experimental Day … Task Force:T Scientific Coordinator:Tuomas Tala / Wayne Solomon Session Leader:Maximos Tsalas Diagnostic Coordinator:Perry Beaumont Engineer in Charge:Cyril Lescure Session Aims:T Dependence of particle and momentum pinch on collisionality Date:Thursday 13/08/09 Shift:EarlyWeek:n/a PulseTimeBtIp P NBI (MW ) P ICRH (MW) n e0 (10 19 m -3 ) T e0 /T i0 (keV)   0 (krad/ s) ICRH (MHz)/p hase He3 (%) Pre & Post Pulse Comme nts :09-DRY-RUN-PVFA3 crowbar :26-DRY-RUN-PVFA3 crowbar :12-DRY-RUN-PVFA3 crowbar

Tuomas Tala 16/16 ITPA TC Meeting, Princeton, USA 5 October – 7 October 2009 Summary of ITPA TC-15  DIII-D and NSTX: produced a good set of data for both momentum and particle transport studies  JET: August 13 session was a complete technical failure, a new day allocated to be October 22.  JT-60U and C-MOD: some data could be possible used to complete the data from the joint experiment  Lots of analysis still to be done and of course the JET part of the experiment  Good interchange of scientists, Wayne participated in all 3 devices and Tuomas travelled to DIII-D (and JET)  Not ready to be closed yet but next time …