ITPA TC-15, Dependence of Momentum and Particle Pinch on Collisionality T. Tala (JET, DIII-D), W. Solomon (DIII-D, JET, NSTX), S. Kaye (NSTX), L.F. Delgado-Aparicio (NSTX), L. Zeng (DIII-D) and L. Garzotti (JET) + large local teams in each tokamak not listed here

Status of TC-15 Joint Experiment: Dependence of Momentum and Particle Pinch on Collisionality XXX Experiment done XXX Experiment planned XXX Experiment provisionally planned XXX Some data exist, but not directly linked to this Joint Experiment Colour codes: Device Momentum Particle Period Local Key Person JET, 22 October 2009 XXX 2009-2011 T. Tala/L. Garzotti DIII-D, 20 May 2009 2009-2010 W. Solomon/L. Zeng NSTX, August 2009 S. Kaye/L. Delgado-Aparicio JT-60U ? M. Yoshida C-MOD 2010 J. Rice / J. Hughes AUG 2010-2011 G. Tardini/F. Ryter

Outline NBI modulation experiments to study the dependence of momentum pinch and Prandtl number on collisionality on JET Particle transport studies from the gas puff modulation experiment on JET and DIII-D Plans on other tokamaks than JET, DIII-D and NSTX (experimental planning status)

A Traditional Collisionality Scan with NBI Modulation on JET (Similarly to DIII-D) increase temperature and decrease collisionality with NBI increase B to correct for β and ρ* adjust Ip to keep q unchanged We should have increased power in the low ν* case (blue curve) more aggressively (problem in jumping to H-mode, these are L-mode plasmas) Still roughly a factor of 4 change in collisionality Gas puff modulation experiment pioneered with new KG10 reflectometry (data not yet analysed in details, but data quality seems good)

ne or R/Ln Matched very well within the Collisionality Scan Matching R/Ln crucial to separate the effect of R/Ln from that of collisionality! R/Ln and q kept fixed very well between the 3 shots Roughly a factor of 4 change in collisionality ρ* matched within 10% and β within 20%

Prandtl Number Independent of Collisionality in a Clean 3-point Scan JET pulses: 79811, 79815 and 79814 Pr does not depend on collisionality What would the theory say? No GK analysis or transport modelling for these shots done. The momentum database by M. Yoshida did not show any clear Pr dependence on collisionality either These are low power (~5MW) L-mode shots while the previous ones were higher power (~10MW) H-mode ν*= 0.005 ν*= 0.011 ν*= 0.018

There Seems to Be a Dependence of Pr on H/L-mode or Heating Power There Seems to Be a Dependence of Pr on H/L-mode or Heating Power. Theory? Low power L-mode plasmas: collisionality scan Medium power H-mode plasmas: Type III ELMy around 10-12MW ν*= 0.005 ν*= 0.011 ν*= 0.018

The Pinch Number Increases with Collisionality Rather clear dependence on collisionality Thus, collisionality must be taken into account when analysing the R/Ln and q scans This dependence opposite of that of particle pinch dependence on collisionality Consequence to ITER? What does the other experiments or theory say? ν*= 0.005 ν*= 0.011 ν*= 0.018

Same ITPA Experiment on DIII-D Shows Qualitatively the Same Trend -Rvpinch/χ decreases with decreasing collisionality on DIII-D and also on NSTX Consistent with JET data W. Solomon APS 2009 This ITPA meeting, Submitted to PoP

GKW Simulations Do Not Find Almost Any Dependence on Collisionality Pr Pr does not depend on collisionality, consistent with the experiment -Rvpinch/χ seems to have almost no dependence on collisionality in GKW simulations not consistent with JET or DIII-D results 10Di/χi -Rvpinch/χ A. Peeters, PoP 2009

Outline NBI modulation experiments to study the dependence of momentum pinch and Prandtl number on collisionality on JET Particle transport studies from the gas puff modulation experiment on JET and DIII-D Plans on other tokamaks than JET, DIII-D and NSTX (experimental planning status)

Reflectometry Data from the Gas Puff Modulation Looks Good on JET Similar procedure to the NBI modulation experimental analysis for momentum Find particle D and V profile that give the best agreement with the amplitude and phase from the reflectometry data by using a transport code. L. Garzotti, TF-T workshop 2010

Preliminary Results from DIII-D Gas Puff Modulation Experiment (TC-15) Similar gas puff modulation collisionality scan carried out on DIII-D in combination with NBI modulation Particle diffusion coefficient and pinch velocity both gradually increase with radius Negative Ve means inward pinch velocity L. Zeng, APS 2009

Outline NBI modulation experiments to study the dependence of momentum pinch and Prandtl number on collisionality on JET Particle transport studies from the gas puff modulation experiment on JET and DIII-D Plans on other tokamaks than JET, DIII-D and NSTX (experimental planning status)

Progress on Other Tokamaks for the ITPA TC-15 Experiment JT-60U: NBI modulation experiments at different collisionalities done, but not in a controlled clean way (only varying collisionality). Probably then some other dependencies, like R/Ln will mask any collisionality dependence. Only momentum transport. C-MOD: The experimental plan is being initiated and should be carried out later in 2010. Both momentum and particle transport is in the plan. AUG: A provisional plan to carry out both the NBI and particle transport part listed in the TC-15 plan during 2010-2011 using the upgraded CX and reflectometry.

Conclusions Prandtl number is independent of collisionality Pinch number -Rvpinch/χ increases with collisionality. Both JET, DIII-D and NSTX (same TC-15 experiment) yield this result. Not captured in ‘general’ gyro-kinetic simulations (no dedicated runs for these plasmas done though). The particle transport analyses from the gas puff modulation experiment initiated, but no firm results yet available.