Simultaneous measurement of time-resolved 2-D temperature distribution of evaporation surface heated by swept electron beam [in AVLIS]

The temporal variation and spatial distribution of metallic gadolinium surface temperature during electron beam evaporation have been measured simultaneously by a high-speed video camera with a bandpass filter. The temperature was determined from the radiation intensity recorded by the bandpass, high-speed video camera coupled with a bandpass filter, after calibration with a two-color thermometer. Analytical results indicate that temporal variation of the surface temperature will cause a significant fluctuation of the atomic beam.

I. Introduction

IN ATOMIC vapor laser isotope separation (AVLIS) [1], the electron beam heating technique, is used to produce the metal atomic vapor containing isotope species selectively photoionized by a pulsed laser beam. Recently, a new sweeping mode electron beam heating technique was proposed to produce a long-distance atomic vapor with high evaporation efficiency [2]. In order to maximize the laser beam efficiency and atomic vapor utilization, the atomic beam must be stable and uniform [3]. Since the qualities of the evaporated atomic beam mainly depend on electron beam heating, it is important to know the spatial and temporal characteristics of the evaporation surface temperature.