Effective erosion coefficient and plasma velocity limitation in the channel of an electromagnetic rail accelerator

The concept of an effective erosion coefficient, which takes into account the capture and entrainment in motion (by accelerated plasma) of only part of the erosion mass lost by rail accelerator electrodes, is introduced to describe the plasma acceleration dynamics in the channel of an electromagnetic rail accelerator. This parameter is determined from a comparison of the experimental and calculated plasma velocities at the stage of velocity saturation. The plasma velocity is calculated using a model that takes into account the pressure force of a shock-compressed gas and the deceleration force that appears during the capture of the erosion mass by a plasma piston. The ratio of the captured mass to the mass lost by the electrodes is found to depend on the current; for copper, this ratio is 1/4–2/3. The effective erosion coefficient is 0.6–0.7 mg/C at a current of ∼40 kA.