Abstract
The shadow image technique was applied to the measurement of the current density distribution, and the power density and the minimum spot diameter in the focal point of the electron beam was calculated. The actual microfocus X-ray unit was established on the basis of the theory of the telefocus electron beam one-step reducing technique. The electron beam traces emitted from the telefocus four-pole electron gun of the unit were obtained by means of a copper plate contamination technique. The power density and the minimum spot diameter on the target were measured, which met the requirement of the microfocus unit, which features large current capacity and sharp-current density distribution.
In the case of in-focus, current density distribution increased in inverse proportion to r4/3 and spherical aberration of the reducing lens relates to a form of distribution. Power density around the least confusion circle approximates 105W/mm2.
The minimum diameter of the X-ray source was estimated at 10μφ, and the spot size of an electron beam was considered smaller because there was back-scattering.
Because the outside diameter of the unit around the focus point was lessened and the X-ray outlet could be located near the X-ray source by employing the long-focus magnetic lens (f: 13cm) in the tele-focus electron gun of the actual unit, efficiency as an X-ray source was improved far better than those of other X-ray units.
The application for the crystal structural analysis of single crystal plates through the divergent X-ray beam radiated from the X-ray source of 10 microns in diameter were indicated with some examples.
