Studies of non-inductive current drive in the CDX-U tokamak

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1993

OSTI ID:7155652

Hwang, Y S

Two types of novel, non-inductive current drive concepts for starting-up and maintaining tokamak discharges, dc-helicity injection and internally-generated pressure-driven currents, have been developed on the CDX-U tokamak. To study the equilibrium and transport of these plasmas, a full set of magnetic diagnostics was installed. By applying a finite element method and a least squares error fitting technique, internal plasma current distributions are reconstructed from the measurements. Electron density distributions were obtained from 2 mm interferometer measurements by a similar least squares error technique utilizing magnetic flux configurations obtained by the magnetic analysis. Neoclassical pressure-driven currents in ECH plasmas are modeled with the reconstructed magnetic structure, using the electron density distribution and the electron temperature profile measured by a Langmuir probe. In the dc-helicity injection scheme, the need to increase injection current and maintain plasma equilibrium restricts possible arrangements. Several injection configurations were investigated, with the best found to be outside injection with a single divertor configuration, where the cathode is placed at the low field side of the x-point. Both pressure-driven and dc-helicity injected tokamaks show the importance of plasma equilibrium in obtaining high plasma current. Programmed vertical field operation has proven to be very important in achieving high plasma current. These non-inductive current drive techniques show great potential as efficient current drive methods for future steady-state and/or long-pulse fusion reactors.

• Research Organization: Princeton Univ., NJ (United States)
• OSTI ID: 7155652
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700350* -- Plasma Production
Heating
Current Drive
& Interactions-- (1992-)
CLOSED PLASMA DEVICES
CYCLOTRON RESONANCE
ELECTRON CYCLOTRON-RESONANCE
ELECTRON DENSITY
ELECTRON TEMPERATURE
LEAST SQUARE FIT
MAXIMUM-LIKELIHOOD FIT
NEOCLASSICAL TRANSPORT THEORY
NON-INDUCTIVE CURRENT DRIVE
NUMERICAL SOLUTION
RESONANCE
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
TRANSPORT THEORY