Accession Number : AD0765336

Title :   Evidence for Surface-State-Enhanced Field Emission in RF Superconducting Cavities,

Corporate Author : STANFORD UNIV CALIF HIGH ENERGY PHYSICS LAB

Personal Author(s) : Schwettman,H. A. ; Turneaure,J. P. ; Waites,R. F.

Report Date : FEB 1973

Pagination or Media Count : 44

Abstract : Measurements of the x-radiation and the electron loading in a niobium cavity resonant in the TM(010) mode at 1208 MHz have been made in order to study enhanced electron field emission in superconducting cavities. Measurements have also been made of the low temperature dc electron field emission from bismuth, niobium, copper and tungsten using a configuration which approximates the point-to-plane geometry. In the rf cavity measurements, it is found that the x-radiation count rate data follows a modified Fowler-Nordheim equation which takes into account the time dependent rf fields, the electron dynamics in the rf fields, the emission of secondary electrons, and the production and absorption of x-radiation. Further, it is found that the x-radiation from the cavity can be reduced by a factor of 10,000 to 1,000,000 by helium-ion sputter processing at low temperature. (Modified author abstract)

Descriptors :   (*SUPERCONDUCTORS, *FIELD EMISSION), MICROWAVE OSCILLATORS, NIOBIUM, BISMUTH, COPPER, TUNGSTEN, SECONDARY EMISSION, X RAYS

Subject Categories : Electricity and Magnetism

Distribution Statement : APPROVED FOR PUBLIC RELEASE