Accession Number : ADP008065

Title :   Multilayer Structures Traversed by Electron Beams as Narrow Line X-Ray Sources,

Corporate Author : JOHNS HOPKINS UNIV BALTIMORE MD DEPT OF ELECTRICAL AND COMPUTER ENGINEERING

Personal Author(s) : Kaplan, A.E. ; Law, C.T.

Report Date : 05 MAR 1992

Pagination or Media Count : 2

Abstract : When an electron beam traverses the interface between two media with different electric constants, the so called transition radiation are generation. In a periodic structure with multiple interfaces, the radiation is greatly enhanced around a spatial region in a conical pattern for certain wavelength. In previous research structures with the thickness of each layer is much longer than the wavelength are used. As a result, ultra-relativistic electrons with energies 100 Mev to 50 Gev 2 are required. However, with advent of new technologies, periodic multilayer structures can be constructed with a spatial period less then 100 A. The generation of soft x rays with a low-energy electron beam that passes through such a multilayer structure was recently proposed. In solid-state structures, the losses due to photoabsorption, and electron scattering may be the main obstacles in x-ray generation with these structures. We showed that the energy of the electron beam from approx. 200 Kev to a few Mev is sufficient to compensate for the loss due to electron scattering. We further demonstrated that above the electron energy of approx. 200 Kev for most of the materials radiating soft x-ray frequency range, the photoabsorption is the limiting factor and electron scattering can be neglected.

Descriptors :   *ELECTRON BEAMS, *LAYERS, *SOFT X RAYS, *STRUCTURES, *X RAYS, CONSTANTS, ELECTRON ENERGY, ELECTRON SCATTERING, ELECTRONS, ENERGY, FREQUENCY, INTERFACES, LOSSES, LOW ENERGY, MATERIALS, MEDIA, PATTERNS, RADIATION, REGIONS, RELATIVISTIC ELECTRONS, SCATTERING, SOLIDS, THICKNESS, TRANSITIONS, DIELECTRICS.

Subject Categories : Radiation and Nuclear Chemistry
      Particle Accelerators
      Nuclear Physics & Elementary Particle Physics
      Electricity and Magnetism

Distribution Statement : APPROVED FOR PUBLIC RELEASE