RESEARCH ON NOISE IN CROSSED FIELD DEVICES
Abstract
Work was directed to a study of the anomalous effects observed in crossed field guns; the more stricking effect is the excess noise which may reach 10 to the fourth power times the thermal noise of the cathode and which causes the sole current in optical systems. The conditions in which such a noise appear are now well known; the spectrum and the correlation in the magnetic field direction have been determined. The theory of the excess noise has not yet been given; the experiments done show that the noise in the gun proceeds from an instability of the space charge which may be modulated by the classical noise; according to this idea, the first step is to find an unstable flow. Up to now only a flow neglecting the space charge or a flow with constant current density has been studied. In this report a flow in which the cathode current is a linear function of the distance on the cathode was theoretically studied; the d-c results, obtained with a digital computer, are given in this report; some critical magnetic fields for which the electron velocities vanish after a particular angle constitute an unexpected phenomenon. On the other hand the computed trajectories permit to design a highly convergent gun which could present some advantages compared to the classical gun assuming a constant density.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1962
- Accession Number
- AD0403986