The Effect of Main-Ion Dilution on Turbulence and Transport in Alcator C-Mod

Paul Ennever; Miklos Porkolab; Matthew Reinke; John Rice; Chris Rost; Naoto Tsujii; Evan Davis; Darin Ernst; Catherine Fiore; Martin Greenwald; Amanda Hubbard; Jerry Hughes; Earl Marmar; Jeff Candy; Gary Staebler; Ron Waltz; Chris Holland

The Effect of Main-Ion Dilution on Turbulence and Transport in Alcator C-Mod

ORAL

Abstract

Previous studies of turbulence using the reduced gyro-landau fluid code TGLF, and the gyrokinetic code GYRO, have predicted that in C-Mod ohmic plasmas a dilution of the main ions by a significant amount causes a reduction of turbulent transport in the ion channel [1]. This could be a factor in the LOC-SOC transition. To test this effect, experiments were performed where nitrogen was puffed into ohmic target plasmas with the density kept constant. This seeding reduced the turbulence in the ion diamagnetic direction as measured by phase contrast imaging. To determine impurity concentrations in the plasma, line brightnesses for the relevant impurity species (N, O, Ar, and Mo) were compared to Zeff from neoclassical conductivity and from continuum measurements. The turbulence and transport simulated with GYRO and TGLF were compared to that measured experimentally. Work supported by US DOE awards DE-FG02-94-ER54235 and DE-FC02-99-ER54512.\\[4pt] [1] M. Porkolab, et al, Bull. Am Phys. Soc. 56, no 12 139 (2011).

Oct. 29, 2012, 10:30 AM – Oct. 29, 2012, 10:42 AM

Authors

Paul Ennever

MIT
Miklos Porkolab

Massachusetts Institute of Technology, MIT-PSFC, MIT PSFC, PSFC MIT, PSFC, MIT, MIT
Matthew Reinke

PSFC-MIT, Massachusetts Institute of Technology, MIT PSFC, MIT-PSFC, MIT - Plasma Science and Fusion Center, MIT
John Rice

MIT-PSFC, MIT, MIT PSFC
Chris Rost

Massachusetts Institute of Technology, MIT
Naoto Tsujii

Massachusetts Institute of Technology, MIT
Evan Davis

MIT-PSFC, MIT PSFC, MIT
Darin Ernst

MIT PSFC, MIT-PSFC, MIT
Catherine Fiore

MIT-PSFC, MIT
Martin Greenwald

MIT-PSFC, PSFC-MIT, Massachusetts Institute of Technology, MIT
Amanda Hubbard

PSFC-MIT, MIT Plasma Science and Fusion Center, PSFC, MIT, MIT PSFC, MIT-PSFC, MIT
Jerry Hughes

PSFC-MIT, MIT Plasma Science and Fusion Center, MIT PSFC, MIT-PSFC, MIT
Earl Marmar

MIT-PSFC, PSFC-MIT, MIT, Mass. Institute of Technology
Jeff Candy

General Atomics
Gary Staebler

General Atomics
Ron Waltz

General Atomics
Chris Holland

UCSD, University of California San Diego, University of California, San Diego, Univ. of California at San Diego