Electron-beam braze welds were made in beryllium by using less than the recommended amount of aluminum filler metal. The welds exhibited a tendency to form microcracks prior to the termination of solidification; however, these microcracks were healed by the backfilling action of the aluminum/beryllium eutectic present in the fusion zone. Adverse effects attributable to the prior microcracking condition were not found.

The orbit-averaged kinetic equation suitable for studying collisional transport in an axisymmetric mirror machine is derived and reduced to a three-dimensional equation in phase space in the case of ..nu../sub c/ << ..omega../sub b/ << ..cap omega.. where ..nu../sub c/ is the collision frequency, ..omega../sub b/ is the bounce frequency, and ..cap omega.. is the gyrofrequency. We found that the gyrophase dependence of the distribution function, ignored in previous Fokker-Planck calculations, is responsible for the diffusion of guiding centers and should be retained when the Larmor radius is comparable to the plasma scale length. The complete Fokker-Planck equation for a square-well magnetic mirror is given as a special case to clarify the approximations and assumptions involved in the radial Fokker-Planck code of Futch. The quasilinear transport code of Matsuda and Berk is also discussed relative to the orbit-averaged Fokker-Planck equation.