Generation of x-rays by irradiating metal surfaces with a powerful laser beam in presence of a strong static electric field

We investigate the generation of high energy x-ray pulses by irradiating me tal surfaces at grazing incidence with a powerful laser beam in the simulta neous presence of a strong static negative voltage in order to explain expe riments by Farkas et al. (Opt, Commun, 21 (1977) 408; ibid 67 (1988) 124). Using the dipole-layer model proposed recently to describe the multiphoton photo-effect at metal surfaces (Phys. Rev. A 57 (1998) 663; J. Phys. D Appl . Phys. 30 (1997) 3071) we are able to explain the essential features of th e above process, in particular its dependence on the strength of the applie d voltage and on the power of the used laser field as well as the maximum p hoton energy emitted. We also present on the basis of our model an estimate of the power of the emitted x-rays in fair agreement with the experimental data. (C) 1999 Elsevier Science B.V. All rights reserved.