This paper describes the theory and design of Rogowski-wound coils used to measure nanosecond electrical curent pulses in the megampere range. The coils have risetimes of less than one nanosecond, microsecond decay times and typical sensitivities in the range of 10−3 to 10−4 V A−1. They operate in large radiation fields, under intense electron bombardment and at high rates of current rise.

Soft x-ray power diagnostics are essential for evaluating high temperature laser plasma experiments. The Dante soft x-ray spectrometer, a core diagnostic for radiation flux and temperature measurements of Hohlraums, installed on the Omega Laser Facility at the Laboratory for Laser Energetics has recently undergone a series of upgrades. Work performed at Brookhaven National Laboratory for the development of the National Ignition Facility (NIF) Dante spectrometer enables the Omega Dante to offer a total of 18 absolutely calibrated channels in the energy range from 50eVto20keV. This feature provides Dante with the capability to measure higher, NIF relevant, radiation temperatures with increased accuracy including a differentiation of higher energy radiation such as the Au M and L bands. Diagnostic monitoring using experimental data from directly driven Au spherical shots is discussed.

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The propagation of a 1.8-MV 80-kA power pulse in a 10-m-long 41.6-Ω impedance coaxial vacuum transmission line has been investigated experimentally. The onset of magnetic insulation has been correlated to attainment of the critical current. Measurements of boundary (cathode) current suggest that 50–60% of the current flows in space charge in the axial direction between the conductors. The pulse sharpens as it propagates and attains a stationary shape. Pulse rise times of 4 ns were observed. Propagation velocities equal to 0.7c have been measured. Power and energy transports as high as 90 and 70% have been observed. The peak power density in the transmission line was 2×109 W cm−2.

A self-integrating search coil with a risetime of approximately 0.4 nsec has been developed for measuring kilogauss magnetic fields in adverse environments. A coaxial calibration fixture with a field risetime of 0.85 nsec was built to calibrate the fluxmeters.