Characterization of Electromagnetic Fields in an Extended Chamber at the ShortPulse Experimental Electron Device (SPEED) Simulator

摘要

The electromagnetic (EM) fields present during testing in a large vacuum chamberat the Short Pulse Experimental Electron Device (SPEED) facility are observed and measured using B-dot and D-dot detectors. Because the cathode of the vacuum diode is exposed to the chamber, the EM fields are significant and could adversely affect nonfaraday-shielded experiments. The differential magnetic fields and electric fields are nearly isotopically distributed, build to a maximum at 100-200 ns of 7.9 x 10 to the 9th power A/m-s and 9 x 10 to the 10th power V/m-s, respectively, then decay for approximately 1000 ns. Fourier analysis of spectra gives frequencies (460, 550, and 60 MHz) characteristic of the dimensions of the chamber and of electrons rebounding between the target and the pulse generators. A collimated damper is designed which should eliminate most EM fields in future tests in this configuration.