1. 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

2. 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
T. Tala/L. Garzotti
DIII-D, 20 May 2009
W. Solomon/L. Zeng
NSTX, August 2009
S. Kaye/L. Delgado-Aparicio
JT-60U ?
M. Yoshida
C-MOD
2010
J. Rice / J. Hughes
AUG
G. Tardini/F. Ryter

3. 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)

4. 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)

5. 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%

6. Prandtl Number Independent of Collisionality in a Clean 3-point Scan
JET pulses: 79811, 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

7. 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

8. 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

9. 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

10. GKW Simulations Do Not Find Almost Any Dependence on CollisionalityPr
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

11. 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)

12. 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

13. 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

14. 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)

15. 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 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 using the upgraded CX and reflectometry.

16. 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.