An electrostatic accelerator for ultrahypervelocity microprojectiles

An electrostatic accelerator technique for microprojectiles is being developed based on a multistage system using the sequential application of moderate-voltage pulses (⩾100 kV). Preliminary experiments have shown that carbon fibers have adequate tensile strength and conductivity to achieve charge-to-mass ratios ⩾1 C/kg, a value consistent with hypervelocity goals. The carbon microprojectiles have been used in a five-stage proof-of-principle prototype accelerator at stage voltages of 35 kV to attain velocities of 0.5 km/s. Through the use of schlieren imaging techniques, data have been obtained showing that good control of the projectile trajectory can be achieved with electrostatic aperture focusing methods. Information from these experiments is being used to design and construct a 10-20 km/s prototype accelerator. To obtain a relatively short accelerator, encapsulation techniques are being developed so that acceleration gradients approaching the high dielectric strengths of the encapsulants can be achieved. A reflex transmission line arrangement has been devised that permits the longitudinal accelerating field to follow the projectile motion along the multiple stages with minimal switch action and without reversing electric field vectors, which would degrade dielectric strength. Details on the accelerator concept, the experimental results, and hardware designs are presented