TMX-U thermal-barrier experiments

Author

Simonen, T.C. ; Allen, S.L. ; Barter, J.D. ; Casper ; Correll, D.L. ; Carter, M.R. ; Clauser, J.F. ; Dimonte, G. ; Foote, J. ; Futch ; Goodman, R.K. ; Grubb, D.P. ; Hill, D.N. ; Hooper ; Hornady, R.S. ; James, R.A. ; Molvik, A.W. ; Nexsen, W.E. ; Porter,

Author_Institution

Lawrence Livermore Nat. Lab., California Univ., Livermore, CA, USA

Volume

16

Issue

1

fYear

1988

fDate

2/1/1988 12:00:00 AM

Firstpage

1

Lastpage

10

Abstract

Thermal-barrier experiments in the Tandem Mirror Experiment Upgrade (TMX-U) are reported, along with progress made at the Lawrence Livermore National Laboratory in plasma confinement and central-cell heating. Thermal barriers in TMX-U improved axial confinement by two orders of magnitude over a limited range of densities, compared with confinement in single-cell mirrors at the same ion temperature. It is shown that central-cell radial nonambipolar confinement scales as neoclassical theory and can be eliminated by floating the end walls. Radial ambipolar losses can also be measured and reduced. The electron energy balance is improved in tandem mirrors to near classical, resulting in T_e up to 0.28 keV. Electron cyclotron heating (ECH) efficiencies up to 42%, with low levels of electron microinstability, were achieved when hot electrons in the thermal barrier were heated to average betas as large as 15%. The hot-electron distribution was measured from X-rays and is modeled by a Fokker-Planck code that includes heating from cavity radio-frequency (RF) fields

Keywords

plasma confinement; plasma devices; plasma heating; plasma instability; plasma temperature; plasma transport processes; plasma waves; plasma-beam interactions; radiofrequency heating; ECH; Fokker-Planck code; ICH; RF heating; TMX-U; Tandem Mirror Experiment Upgrade; X-rays; axial confinement; central-cell heating; central-cell radial nonambipolar confinement scales; electron cyclotron heating; electron energy balance; electron microinstability; end wall floating; hot-electron distribution; ion cyclotron heating; ion temperature; neoclassical theory; neutral beam injection; plasma confinement; single-cell mirrors; thermal barrier; thermal-barrier experiments; Cyclotrons; Electrons; Heating; Laboratories; Loss measurement; Mirrors; Plasma confinement; Plasma temperature; Radio frequency; Temperature distribution;

fLanguage

English

Journal_Title

Plasma Science, IEEE Transactions on

Publisher

ieee

ISSN

0093-3813

Type

jour

DOI

10.1109/27.3782

Filename

3782