MEASUREMENT OF CESIUM EXCITATION CROSS SECTION NEAR THRESHOLD BY A SWARM TECHNIQUE
Abstract
Electron drift velocities were measured in cesiumargon mixtures for E/N values between 3 x 10 to the -19th power and 5 x 10 to the -18th power V-sq cm and cesium to argon concentration ratios between to the -8th power and 10 to the -5th power. The drift velocity was obtained from measurements of the electron transit time using an ac technique which is a modification of a technique developed originally by Rutherford for ion drift velocity measurements. Numerical solutions of the Boltzmann transport equation were used to determine an excitation cross section which is consistent with the experimental drift velocity data. For a single excitation threshold at 1.386 EV, the best slope for a linear cross section is 7.1 x 10 to the -15th power sq cm/eV. If excitation to the 6 P-1/2 and 6 P3/2 states is considered separately, with thresholds at 1.386 eV and 1.454 eV respectively, the linear cross sections obtained have a slope of 2.5 x 10 to the -15th power sq cm /eV for 6 P-1/2 excitation, and 5.0 x 10 to the -15th power sq cm/eV for 6 P-3/2 excitation. The range of validity of these values is from threshold up to about 1.8 eV. other shapes for the cross section are investigated. The experimental cross section is in reasonable agreement with extrapolations of theoretical cross sections.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 15, 1965
- Accession Number
- AD0615163
Entities
People
- Arthur V. Phelps
- J. F. Nolan