Calibration of X-Ray Film Used in the Detection of Soft X-Rays from the CTR Device Sceptre

Abstract

To assist in the interpretation of X-ray pinhole photographs in thermonuclear research with the toroidal pinch device Sceptre, with a view to applying such photographs to the study of the energy spectrum of the electron flux incident upon the torus walls (constructed from aluminium and copper), experiments have been performed to determine the photographic effect of the X-rays produced from a known flux of electrons of given energy. A demountable X-ray tube was made in which the target was alternately copper or aluminium foil, indirectly heated, and in which a beam of electrons of known energy was focused on the foil. X-rays from the target fell upon llford Industrial G type X-ray flim, after passing through one or more metal foils. By maintaining a known beam current for different times, a range of exposures was given to different parts of the same film specimen and density-log exposure curves were compiled. Results of such experiments are presented for target elements of aluminium and copper and various thicknesses of absorbing foil, for electron energies in the range 1.8-8.4 KeV. A method is suggested by which data accumulated in this way may be used in analysis of electron energy spectra.