A Technique to Measure High-Power Electron Beam Currents

A technique has been used to measure electron beams in excess of 200 kA/cm2 with energies of 105−106 eV. The technique uses a high-level nanosecond risetime Faraday cup combined with a dielectric differential range filter to separate the primary electrons from low-energy charge carriers in the transport system. This technique has been the one used to measure primary beam currents in excess of 5×105 A with pulsewidths on the order of 100 nsec. When combined with a knowledge of particle energy, power flux and deposition profiles may be inferred. A derivation of the electric field generated at the cup collector is included.