Particle fueling and impurity control in PDX

Conference · Sat Dec 01 04:00:00 EST 1984

OSTI ID:6209324

Fonck, R J; Bell, M; Bol, K; Budny, R; Couture, P; Darrow, D; Dylla, H; Goldston, R; Grek, B; Hawryluk, R

Fueling requirements and impurity levels in neutral-beam-heated discharges in the PDX tokamak have been compared for plasmas formed with conventional graphite rail limiters, a particle scoop limiter, and an open or closed poloidal divertor. Gas flows necessary to obtain a given density are highest for diverted discharges and lowest for the scoop limiter. Hydrogen pellet injection provides an efficient alternate fueling technique, and a multiple pellet injector has produced high density discharges for an absorbed neutral beam power of up to 600 kW, above which higher speeds or more massive pellets are required for penetration to the plasma core. Power balance studies indicate that 30 to 40% of the total input power is radiated while approx. 15% is absorbed by the limiting surface, except in the open divertor case, where 60% flows to the neutralizer plate. In all operating configurations, Z/sub eff/ usually rises at the onset of neutral beam injection. Both open divertor plasmas and those formed on a well conditioned water-cooled limiter have Z/sub eff/ less than or equal to 2 at the end of neutral injection. A definitive comparison of divertors and limiters for impurity control purposes requires longer beam pulses or higher power levels than available on present machines.

• Research Organization: Princeton Univ., NJ (USA). Plasma Physics Lab.
• DOE Contract Number: AC02-76CH03073
• OSTI ID: 6209324
• Report Number(s): PPPL-2175; CONF-840520-28; ON: DE85005350
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700202 -- Fusion Power Plant Technology-- Magnet Coils & Fields
700209* -- Fusion Power Plant Technology-- Component Development & Materials Testing
BEAM INJECTION
CLOSED PLASMA DEVICES
DIVERTORS
ELEMENTS
ENERGY BALANCE
FLUID FLOW
FUEL PELLETS
GAS FLOW
HYDROGEN
IMPURITIES
LIMITERS
NEUTRAL ATOM BEAM INJECTION
NONMETALS
PDX DEVICES
PELLETS
REACTOR FUELING
THERMONUCLEAR DEVICES
TOKAMAK DEVICES