# Presentation: 475256

## Scaling of impurity (Ne & Ar) transport in beam heated NSTX H-mode discharges

- L. F. Delgado-Aparicio, D. Stutman, K. Tritz, and M. Finkenthal
- The Johns Hopkins University, The Plasma Spectroscopy Group
- R. E. Bell, R. Kaita, S. Kaye, B. P. LeBlanc, S. Paul,
- L. Roquemore and D. Smith
- Princeton Plasma Physics Laboratory
- F. Levinton, H. YuhNOVA Photonics, Inc.

**NSTX, ****results meeting**** **
- Monday, July 22, 2007
- Princeton, New Jersey, USA

## Abstract

**Motivation**
-       Perform particle transport studies in high (Power & **) performance
-       NSTX H-modes, important for NSTX and the next-step ST.

**Experiment**
-        i) **Neon** injected in **MHD quiescent** high-** high confinement H-modes.
-        ii) The main diagnostic used was the **“multi-color” optical SXR array**.
-       iii) *B* & *I**p* scanned at fixed *q*-profile for ********* scaling** experiments.

-  **D****Z** (diffusion) & **v****Z** (convective velocity)
-  Identify regimes with possible **impurity “screening” (v****Z****>0)**.
-  ************* scaling at ***fixed q-profile, ***
-  ***I******p****** and B************ scaling***

## Experimental requirements and issues during XP 716

**Experimental requirements**
-  Sources A & B @ 90 kV, and source C @ 70 kV
-  Turn of source C @ 300 ms
-  Impurity injection @ 350 ms

**Issues during XP 716**
-  Source B had to be turned off. Worked at 4 MW with sources A & C
-  Multiple ELMs and possible inboard MARFE activity
-  Try to reduce the ELM activity by changing the CS fueling
-  MHD activity in 5.5 kG shots
-  H-mode   L-mode  H-mode (change timings)
-  Impossible to achieve good conditions @ 0.8 MA  0.9 MA
-  Control access for TVPS PLC
-  Failed to open shutters (TIVs) for good Ar injection!

## Neon injection at 4.5 kG and 1.0 MA (121032 & 121031)

**Neon, t********[400,406]ms**

**CORE**
**MID-RADIUS**
**EDGE**

**Did MHD **
- [e.g. ELMs, MARFEs or (*m*,*n*) modes]** **
**shield the core from impurities?**

## Argon injection at 4.5 kG and 1.0 MA (121036 & 121035)

- Argon injection at 4.5 kG and 1.0 MA (121036 & 121035)

**Argon, t********[400,410]ms**

**CORE**
**MID-RADIUS**
**EDGE**

## Neon injection at 5.5 kG and 1.0 MA (121017 & 121015)

**Neon, t********[350,360]ms**

**CORE**
**MID-RADIUS**
**EDGE**

## Neon injection at 5.5 kG and 1.2 MA (121030 & 121029)

- Neon injection at 5.5 kG and 1.2 MA (121030 & 121029)

**Neon, t********[420,430]ms**

**CORE**
**MID-RADIUS**
**EDGE**

-  ***Background:*** H-L-H-mode conditions @ 390 ms. ***E* and *S**n* increased strongly when in L-mode
-  ***Neon seeded***: Do not have the H-L-H transitions. **E and *S**n* increased when gas is injected!

***MHD***

## Future work

-  Invert line-integrated data to obtain SXR emissivity profiles.
-  Run MIST code. Possible need of time-dependent (*D**Z* & *V**Z*) analysis.
-  Establish (if possible) impurity scaling at 4.5 kG and 1.0 MA.
-  Investigate the role of MHD and ELMs in shielding the core.
-  Study the transport reduction at high current during the *I**p* scaling (5.5 kG – 1.0 MA vs. 5.5 kG – 1.2 MA)
-  Find out why ***E* and *S**n* increased when gas was injected.