Laser-electron beam interaction applied to optical amplifiers and oscillators

Momentum modulation of a relativistic electron beam by a Nd:YAG laser is demonstrated. The electrons, at 100 MeV energy, interact with the laser light in helium gas at standard temperature and pressure. At an angle of 6.55 mrad between the two wavevectors, corresponding to the Cerenkov angle, a given electron remains in a field of constant phase as it passes through the light beam. The experimental arrangement is illustrated showing the trajectories of the electron and light. The particle momentum is measured by a mass spectrometer, and the angle between the wavevectors is controlled by a rotatable mirror. Experimental results indicate that momentum modulation of an electron beam may be used for amplification. A possible configuration for an optical klystron is illustrated

X-ray Cherenkov radiation under conditions of grazing incidence of relativistic electrons onto a target surface

X-ray Cherenkov radiation in the vicinity of the photoabsorption edge of a target is considered in this workyesBelgorod State Universit

Effect of anomalous photoabsorption on parametric X-ray radiation from relativistic electrons

Parametric X-ray radiation from relativistic electrons moving in a crystal is theoretically investigated in Bragg geometry. It is shown that the effect of anomalous photoabsorption can manifest itself within this geometry of the scattering of the pseudophoton field of a fast particleye

X-ray generation from relativistic electrons passing through thin targets in cyclical accelerators

The characteristics of quasi-monochromatic tunable X-ray sources based on multipasses of electrons through thin targets installed in cyclical accelerators are discussed. An internal bremsstrahlung radiator coupled with a multilayer X-mirror placed outside the accelerator vacuum chamber is used to produce tunable, narrow spectrayesBelgorod State Universit

Projection-type X-ray microscope based on a spherical compound refractive X-ray lens

New projection- type X-ray microscope with a compound refractive lens as the optical element is presented. The microscope consists of an X-ray source that is 1-2 mm in diameter, compound X-ray lens and X-ray camera that are placed in-line to satisfy the lens formula. The lens forms an image of the X-ray source at camera sensitive plate. An object is placed between the X-ray source and the lens as close as possible to the source, and the camera shows a shadow image of the object. Spatial resolution of the microscope depends on the lens focal length, lens aperture and the distance from the source to the object. One to two micron resolution may be achieved by placing the object at a distance of 1-5 mm from the source. The X-ray source may be designed with the target deposited on a 200-µm thick Be window, which permits the object to be placed very close to the emitting surface. The tube focal spot is equal to 1-2 mm. Results of imaging experiments with an ordinary copper anode X-ray tube and a 10-cm focal length spherical compound refractive X-ray lens are discussed

Microspot x-ray focusing using a short focal-length compound refractive lenses

We have fabricated and tested short focal-length compound refractive lenses (CRLs) composed of microbubbles embedded in epoxy encased in glass capillaries. The interface between the bubbles formed 90 to 350 spherical biconcave microlenses reducing the overall focal length inversely by the number of lenses or bubbles. When compared with CRLs manufactured using other methods, the microbubble lenses have shorter focal lengths with higher transmissions and larger gains for moderate energy x rays (e.g., 7–20 keV). We used beamline 2–3 at the Stanford Synchrotron Radiation Laboratory and beamline 5BM-D-DND at the Advanced Photon Source to measure focal lengths between 100–250 mm with lens apertures varying between 97 and 321 mm. Transmission profiles were measured giving, for example, a peak transmission of 46% for a 240 mm focal length CRL at 20 keV. The focal-spot sizes were also measured yielding, for example, a vertical spot size of 1.2 mm resulting from an approximate 20-fold demagnification of the APS 23 mm source size. The measured gains in intensity over that of unfocused beam were between 9 and 26

A method for measuring dark current electron beams in an rf linac

X-ray fluorescence from thin foils inserted into the NPS linac has been used to measure the integrated electron beam intensity when the accelerator is operating with dark current. The measured x-ray flux, the known inner shell ionization cross sections and radiative transition probabilities are used to obtain measurements of dark currents of the order of 10{sup -14} amperes. The same arrangement allows continuous, in-situ energy calibration of our SiLi detector in the electromagnetic noise environment of the linac. This technique was orginally developed to perform absolute production efficiency measurements of parametric x-ray generation in the 5-50 keV range