To generate soft x-rays/UV you don't really need an accelerator, since high voltage (not that high actually, since required kilovolts can easily be achieved) is

To generate soft x-rays/UV you don't really need an accelerator, since high voltage (not that high actually, since required kilovolts can easily be achieved) is enough to produce photons of those energies. Vaporization you mention is likely because of electrons hitting the material, since in any case to emit photons electrons need to be slowed down. Either electrical potential difference in a vacuum chamber or an actual accelerator is being used, the material to brake electrons will evaporate anyway.