The Physics of Confinement Improvement with Impurity Seeding in DIII-D
Description/Abstract
Clear increases in confinement (from H{sub 89P} {approx} 1 to H{sub 89P} {<=} 2) and simultaneous reductions of long-wavelength turbulence have been observed in L-mode discharges in DIII-D, which are directly correlated with external impurity injection [1]. These observations provide an opportunity to understand the mechanism for confinement improvement with impurity seeding observed in a number of tokamaks [2], and to make quantitative tests of theory-based turbulence and transport models with experimental measurements. Impurity seeding can be used not only to produce a radiative mantle to reduce heat fluxes to the first wall material [3], but also as a tool to control profiles in Advanced Tokamak (AT) plasmas. Significant confinement improvements are observed with injection of noble gases (Ne, Ar, and Kr) into L-mode edge, negative central shear (sawtooth-free) discharges in DIII-D. Compared to similar reference discharges without impurity injection, confinement enhancement factor and neutron emission in neon-injected discharges are nearly doubled [Fig. 1(a,b)]. The ion and electron temperature with neon injection exhibit increased central values and profile broadening while the electron density profile becomes more peaked.
| Creator/Author: | M. Murakami ; G.R. McKee ; G.L. Jackson ; G.M. Staebler ; D.R. Baker ; J.A. Boedo ; N.H. Brooks ; K.H. Burrell ; D.R. Ernst ; T.E. Evans ; C.M. Greenfield ; R.J. Groebner ; J.E. Kinsey ; R.J. La Haye ; L.L. Lao ; A. Messiaen ; J. Mandrekas ; J. Ongena ; C.L. Rettig ; B.W. Rice ; D.W. Ross ; H.E. St.John ; R.D. Sydora ; D.M. Thomas ; M.R. Wade ; W.P. West |
|---|---|
| Publication Date: | 2000 Aug 01 |
| OSTI Identifier: | OSTI ID: 766728 |
| Report Number(s): | GA-A23443 |
| DOE Contract Number: | AC03-99ER54463; AC05-00OR22725; AC02-76CH03073; W-7405-ENG-48; FG03-86ER53225; FG03-95ER54294; FG03-96ER54373; FG03-97ER54415; FG03-92ER54141 |
| Other Number(s): | TRN: US0109347 |
| Resource Type: | Conference |
| Resource Relation: | Conference: 27th European Physical Society Conference on Controlled Fusion and Plasma Physics, Budapest (HU), 06/12/2000--06/16/2000; Other Information: PBD: 1 Aug 2000 |
| Research Org: | General Atomics, San Diego, CA (US) |
| Sponsoring Org: | US Department of Energy (US) |
| Subject: | 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; L-MODE PLASMA CONFINEMENT; DOUBLET-3 DEVICE; ELECTRON DENSITY; ELECTRON TEMPERATURE; FIRST WALL; NEUTRON EMISSION; RARE GASES; TURBULENCE; ION TEMPERATURE; GAS INJECTION; NEON |
| Country of Publication: | United States |
| Language: | English |
| Format: | Size: 7 pages |
| Availability: | INIS; OSTI as DE00766728 To purchase this media from NTIS, click here |
| Update Date: | 2008 Feb 05 |
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