Abstract: Surface research for controlled thermonuclear fusion

Abstract

The ERDA surface science research program for controlled thermonuclear fusion is closely coordinated with the general schedule for fusion power development, including the Tokamak Fusion Test Reactor (TFTR) in 1980, an Experimental Power Reactor (EPR) in 1985, and a Demonstration Plant (DEMO) in 1998. Consistent with this schedule, the program is based on the following objectives:(1) To treat surface effects from the standpoints of plasma contamination, wall erosion, and device efficiency.(2) To contribute to the solution of problems in confinement experiments over the near term while developing the data base for dealing with possibly more severe problems in reactors.(3) To view surfaces as part of a completely integrated system consisting of the plasma and its perimeter, the external blanket, subsystems for vacuum pumping, fueling and ash removal, and possibly bumpers or divertors.(4) To screen a number of materials to identify those that merit long‐range development.(5) To provide for correlation of experimental results by including a wide variety of experimental techniques in the program.(6) To couple experimental observations with strong theoretical support seeking fundamental understanding of surface processes as they relate to CTR, rather than an exhaustive cataloging of data.With these general guidelines, surface work is carried out on the following individual processes:(1) Desorption by (a) photons, (b) electrons, (c) ions and neutrals, and (d) thermally.(2) Sputtering by (a) hydrogen ions, (b) residual gas ions (O+, N+, etc.), (c) helium, (d) metallic ions (self‐sputtering), and (e) neutrons.(3) Hydrogen–wall interaction by (a) absorption, (b) diffusion, (c) surface migration, and (d) reflection.(4) Blistering, flaking, and surface erosion by (a) incident hydrogen and (b) helium from the DT reaction, (n, α) reactions, and tritium decay.(5) Chemical reactions involving (a) hydrogen and carbon, (b) residual contaminants, (c) carbon and metals (NbC), and (d) decomposition, principally of insulators.(6) Electron emission. Studies of two of these processes occurring at one time are now beginning and will be extended to studies investigating the synergistic effects of three or more processes. These studies are designed to simulate the effects of a burning DT plasma since the latter will not be available for several years.