X-RAY SOURCE

摘要

An X-ray source has a target anode (66) which has a conical apex portion (68) having a comparatively small angle (a1) and a conical base portion (70) having a larger angle (a2). The electron beam is, in use, directed at an inner surface region of the apex portion. The small angle of the apex portion increases the area which is impinged by the electrons, thus facilitating cooling and permitting a higher intensity to be achieved, and also reduces the apparent source size, thereby improving resolution. The apex and base portions may be of different materials (e.g. palladium and nickel or Ni/Cu alloy respectively) so that unwanted X-rays due to stray electrons bombarding the base portion are of such a wavelength as to be comparatively innocuous.