A three-barrel repeating pneumatic pellet injector for plasma fueling of the Joint European Torus

Conference · Thu Jan 01 04:00:00 EST 1987

OSTI ID:5997625

Combs, S K; Milora, S L; Baylor, L R; Foust, C R; Gethers, F E; Sparks, D O

Pellet fueling, the injection of frozen hydrogen isotope pellets at high velocity, has been used to improve plasma performance in various tokamak experiments. In one recent experiment, the repeating pneumatic hydrogen pellet injector was used on the Tokamak Fusion Test Reactor (TFTR). This machine gun-like device, which was developed at the Oak Ridge National Laboratory (ORNL) with an objective of steady-state fueling applications, was characterized by a fixed pellet size and a maximum repetition rate of 4 to 6 Hz for several seconds. It was used to deliver deuterium pellets at speeds ranging from 1.0 to 1.5 km/s into TFTR plasma discharges. In the first experiments, injection of single, large (nominal 4-mm-diam) pellets provided high plasma densities in TFTR (1.8 x 10/sup 14/ cm/sup -3/ on axis). After a conversion to smaller (nominal 2.7-mm-diam) pellets, the pellet injector was operated in the repeating mode to gradually increase the plasma density, injecting up to five pellets on a single machine pulse. This resulted in central plasma densities approaching 4 x 10/sup 14/ cm/sup -3/ and n tau values of 1.4 x 10/sup 14/ cm/sup -3/s. For plasma fueling applications on the Joint European Torus (JET), a pellet injector fashioned after the prototype repeating pneumatic design has been developed. The versatile injector features three repeating guns in a common vacuum enclosure; the guns provide pellets that are 2.7, 4.0, and 6.0 mm in diameter and can operate independently at repetition rates of 5, 2.5, and 1 Hz, respectively. The injector has been installed on JET. A description of the equipment is presented, emphasizing the differences from the original repeating device. Performance characteristics of the three pneumatic guns are also included.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5997625
• Report Number(s): CONF-871125-1; ON: DE88000330
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700205* -- Fusion Power Plant Technology-- Fuel
Heating
& Injection Systems
DEUTERIUM
ELEMENTS
FLUID MECHANICS
FUEL INJECTION SYSTEMS
FUEL SYSTEMS
HYDROGEN
HYDROGEN ISOTOPES
ISOTOPES
JET TOKAMAK
LIGHT NUCLEI
MECHANICS
NONMETALS
NUCLEI
ODD-ODD NUCLEI
PELLET INJECTION
PLASMA DENSITY
PNEUMATICS
STABLE ISOTOPES
TFTR TOKAMAK
THERMONUCLEAR REACTORS
TOKAMAK TYPE REACTORS