49th Annual Meeting of the Division of Plasma Physics
Volume 52, Number 11
Monday–Friday, November 12–16, 2007;
Orlando, Florida
Session TI2: Plasma Technology, Nozzles, and the First Wall
9:30 AM–12:30 PM,
Thursday, November 15, 2007
Rosen Centre Hotel
Room: Salon 3/4
Chair: David Ruzic, University of Illinois
Abstract ID: BAPS.2007.DPP.TI2.6
Abstract: TI2.00006 : Lithium Surface Coatings and Improved Plasma Performance in NSTX*
12:00 PM–12:30 PM
Preview Abstract
Abstract
Author:
H.W. Kugel
(Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543)
NSTX research on lithium-coated plasma facing components is the
latest step in a decade-long, multi-institutional research
program to develop lithium as a plasma-facing system that can
withstand the high heat and neutron fluxes in a DT reactor. The
NSTX research is also aimed towards sustaining the current non-
inductively in H-mode plasmas which requires control of both
wall recycling and impurity influxes. Employing several
techniques to coat the plasma facing components (PFCs) with
lithium, NSTX experiments have shown, for the first time,
significant benefits in high-power divertor plasmas. Lithium
pellet injection (LPI) uses the plasma itself to distribute
lithium on the divertor or limiter surfaces. The multi-barrel
LPI on NSTX can introduce either lithium pellets with masses 1 -
5 mg or powder during a discharge. This significantly lowered
recycling and reduced the density in a subsequent NBI-heated,
divertor plasma. Lithium coatings have also been applied with a
LIThium EvaporatoR (LITER) that was installed on an upper vacuum
vessel port to direct a collimated stream of lithium vapor
toward the graphite tiles of the lower center stack and
divertor. The lithium was evaporated either before tokamak
discharges, or continuously between and during them. By
evaporating lithium into the helium glow discharge that
typically precedes each tokamak discharge, a coating of the
entire PFC area was achieved. Lithium depositions from a few mg
to 1 g have been applied between discharges. Among the effects
observed in subsequent neutral-beam heated plasmas were
decreases in oxygen impurities, plasma density, and the
inductive flux consumption, and increases in electron
temperature, ion temperature, energy confinement and DD neutron
rate. In addition, a reduction in the ELM frequency, including
their complete suppression, was achieved in H-mode plasmas.
Additional observations, such as, the duration of the lithium
coatings, increases in core metal impurity radiation, and
diagnostic window depositions will also be discussed.
*Work supported by US DOE Contract DE-AC02-76CH03073.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2007.DPP.TI2.6