# Presentation: 896300

## Particle transport dependence with beam power in NSTX H-modes

- L. F. Delgado-Aparicio, K. Tritz, D. Stutman and M. Finkenthal
- The Johns Hopkins University, The Plasma Spectroscopy Group
- R. E. Bell, M. Bell, S. Kaye, B. P. LeBlanc, E. Mazzucato, S. Paul,
- L. Roquemore
- Princeton Plasma Physics Laboratory
- F. Levinton, H. Yuh
- NOVA Photonics, Inc.
- K. C. Lee
- University of California at Davis

- PPPL - NSTX research meeting
- December 8th-9th, 2008
- Princeton, New Jersey, USA

## Neon transport improves with PNBI

- Neon transport improves with PNBI

- 127941, H-mode, 0.9 MA, 5.5 kG, NBI: 4→4 MW, tNe[0.35,0.36], 1.5 torr*l*/s
- 127942, H-mode, 0.9 MA, 5.5 kG, NBI: 4→6 MW, tNe[0.35,0.36], 1.5 torr*l*/s

- edge

- edge

- edge

- core

- core

- core

- Transport improvement is observed as an accumulation of neon
- (shell of emission) at the edge

**NBI step**

**NBI step**

**NBI step**

## Neoclassically there is no difference in DPS due to change in rotation

- Neoclassically there is no difference in *D**PS* due to change in rotation

- Romanelli, PPCF, **40**, 1767, (1998).

- 127941, H-mode, NBI: 4→4 MW
- 127942, H-mode, NBI: 4→6 MW

- Transport improvement (less accumulation) due likely a change in
- the convective pinch velocity

## Change of kinetic profiles that could modify particle pinch

*Poloidal-rotation driven convective flux*

- Sources for a convective velocity

*Turbulent convective*
*fluxes (r/a~0.6-0.9)*
- Thermodifussion pinch (*V**Td*).
- Curvature pinch (*V**Cu-TEP*).
- Compression pinch (*V**Co*).

*Losses of electrons *
*(due to GAE’s) could also affect particle transport*

- Observations on Alcator:
- K. Molvig, J. E. Rice,
- and M. S. Tekula, PRL, (1978).
- J. E. Rice, K. Molvig, and H. I. Helava, Phys. Rev. A, (1982).

- Work  with K. Tritz on applying neon injection on a variety of shots
- before NBI beam steps.

*poloidal*
*CHERS*

## EXTRAS

## Correlation between high power and electron and particle transport ?

**3.0 MW**

**4.0 MW**

**4.6 MW**

**5.0 MW**

- The carbon density profiles seem to be hollow at higher power

-  C and/or Ne injection could tackle this problem

*T**e0* flattening and increase ***T**e*(r/a~0.5-0.8) at high *V**b*

## Similar results observed also at high field

-  Neoclassicaly *V**Z**>0* in both low- and high-field conditions.
-  *V**Z*<0 at r/a>0.5 at low-field is anomalous (MHD, ITGs/TEM/ETG s).
-  **Is the anomaly in the pinch velocity because of lack of shear suppression ?**

## “Non-classical” particle pinch through gradients, collisionality and Er

- “Non-classical” particle pinch through gradients, collisionality and *E**r*

- Turbulent convection (I) – The thermodifussion pinch (*V**Td*)

- Turbulent convection (II) – The curvature pinch (*V**Cu-TEP*)

- Turbulent convection (III) – The compression pinch (*V**Co*)

-  **Use beam steps to change kinetic gradients!**
-  Use He, C, **Ne for impurity transport**.
-  Would be nice to probe with core electron heating.

-  Change *q*-profile (shear) through elongation.
-  **Reduce *****q******95***** by increasing current at low field.**

- The “fast-electrons” pinch (*V**GAE*)

-  Driven by the electric field from the loss of trapped electrons.
-  **Use beam steps to increase GAE activity and probe with Ne for impurity transport**.

-  Found in turbulent transport simulations with artificial Z/A; weak effect
-  Dependence on *T**e**/T**i * in dominant *T**e* heating scenarios [reverse sign (+)].