EXTRUDER SYSTEM FOR HIGH-THROUGHPUT STEADY-STATE HYDROGEN ICE SUPPLY AND APPLICATION FOR PELLET FUELING OF REACTOR-SCALE FUSION EXPERIMENTS/

Pellet injection systems for the next-generation fusion devices, such as the proposed International Thermonuclear Experimental Reactor (ITER ), will require feed systems capable of providing a continuous supply of hydrogen ice at high throughputs. A straightforward concept in whic h multiple extruder units operate in tandem has been under development at the Oak Ridge National Laboratory. A prototype with three large-vo lume extruder units has been fabricated and tested in the laboratory. In experiments, it was found that each extruder could provide volumetr ic ice flow rates of up to similar to 1.3 cm(3)/s (for similar to 10 s ), which is sufficient for fueling fusion reactors at the gigawatt pow er level. With the three extruders of the prototype operating in seque nce, a steady rate of similar to 0.33 cm(3)/s was maintained for a dur ation of 1 h. Even steady-state rates approaching the full ITER design value (similar to 1 cm(3)/s) may be feasible with the prototype. Howe ver, additional extruder units (1-3) would facilitate operations at th e higher throughputs and reduce the duty cycle of each unit. The proto type can easily accommodate steady-state pellet fueling of present lar ge tokamaks or other near-term plasma experiments.