A power-voltage scaling law for liquid anode X-ray tubes

An analysis is presented of the relative magnitudes of factors affecting the specific loadability (W mm(-2) K-1) of liquid metal anode X-ray sources (LIMAX). These factors are to a certain extent analogous to those, such as focus width, focus-anode relative sweep velocity and the anode thermal conductivity, of importance in solid-state (e.g. rotating anode) X-ray tubes. It is shown that in general, convection cooling of the electron window by the liquid metal stream represents the least efficient thermal transport process in LIMAX. As the energy deposited in the electron window through inelastic electron scattering is approximately inversely proportional to electron energy, the power loadability of a LIMAX source operated under constant conditions scales to first approximation with the square of the tube potential. This power-voltage scaling law of liquid metal anode X-ray sources is without analogue in solid-state X-ray sources. A summary is presented of potential applications of high continuous power X-ray sources operating in the high-voltage region of several 100 kV. (c) 2004 Elsevier Ltd. All rights reserved.