Vacuum-ultraviolet emission from high-pressure xenon and argon excited by high-current relativistic electron beams

Abstract

High pressure Xe and Ar were excited by high-current relativistic-electron bursts. The spectral and temporal characteristics of the uv continua, centered near 1700 Å in Xe and 1260 Å in Ar, were measured. The maximum of the Xe spectral distribution shifted from 1690 ± 9 to 1710 ± 9 Å, and the spectral width decreased from 150 ± 3 to 110 ± 3 Å when the pressure was raised from 2 to 34 atm. The shift of the Ar continuum centered at 1260 ± 9 Å was negligible and the spectral width decreased from 130 ± 3 to 90 ± 3 Å when the pressure was raised from 2 to 61 atm. Exponential time constants for the buildup and decay of the Xe and Ar continua were obtained. They are characterized by a $p^{-1.5\mathrm{}}$ pressure dependence below 3 atm. Pressure-independent decay time constants of 4 ± 1, 16 ± 2.5, and about 280 nsec were obtained for Xe at high pressure. For Ar the pressure-independent decay time constants were 6 ± 1.5, 30 ± 5, and about 230 nsec. The efficiency for conversion of electron kinetic energy to uv energy was 10 ± 4% in Xe and 15 ± 7% in Ar.