Plasma parameters of an active cathode during relativistic magnetron operation

Abstract

The results of time- and space-resolved spectroscopic studies of the plasma produced at the surface of the ferroelectric cathode during the operation of an S-band relativistic magnetron generating ∼50 MW microwave power at f=3005 MHz and powered by a linear induction accelerator (LIA) (150 kV, 1.5 kA, 250 ns) are presented. The surface plasma was produced by a driving pulse (3 kV, 150 ns) prior to the application of the LIA accelerating high-voltage pulse. The cathode plasma electron density and temperature were obtained by analyzing hydrogen Hα and Hβ, and carbon ions CII and CIII spectral lines, and using the results of nonstationary collision radiative modeling. It was shown that the microwave generation causes an increase in plasma ion and electron temperature up to ∼4 and ∼7 eV, respectively, and the plasma density increases up to ∼7×1014 cm−3. Estimates of the plasma transport parameters and its interaction with microwave radiation are also discussed.

23 GHz ferroelectric electron gun based gyrotron

“…The difficulties of implementing a ferroelectric cathode in microwave tubes were met and overcome for the following devices, a cyclotron resonance maser ͑CRM͒, 7,8 a gyrotron, [9][10][11] a traveling wave tube ͑TWT͒, 12,13 a free electron laser ͑FEL͒, 14,15 and for magnetron interactions. 16,17 The frequencies at which these devices were operated are listed in Table I. The frequencies obtained were in the microwave regime ͑2-10 GHz͒.…”