Effect Of Beam Parameters Research Articles

The UCLA high gain infrared free electron laser

A high gain SASE FEL amplifier designed to operate in the infrared (near 10 μm) is being commissioned in the Particle Beam Physics Laboratory at UCLA. The high brightness beam needed to drive the FEL is provided by an RF photocathode gun employing solenoidal emittance compensation. A novel linac (a Plane Wave Transformer) accelerates the beam to a final energy ≤ 15 MeV. This beam is to be sent through a 60 cm long undulator with a period of 1.5 cm and an undulator parameter K ≈ 1. Near future experiments will focus on FEL physics relevant to proposed short wavelength devices. Investigations of start-up from noise (SASE), effects of beam parameters on gain as well as noise fluctuations are of particular interest. Here we present an overview of the hardware including relevant diagnostics, measured beam parameters, FEL simulation results and the status of proposed experiments.

Cathodoluminescence microscopy of high T c superconducting YBCO and BSCCO materials

Spectroscopic and imaging cathodoluminescence (CL) microscopy has been used to study high T c YBCO and BSCCO superconducting thin films and pellets in the scanning electron microscope. The effects of beam parameters, such as voltage, current, and diameter, have been investigated with a view to optimizing the CL signal intensity whilst preventing sample damage. Limiting the CL signal generation volume to within the thin film is important in eliminating any substrate contribution. Areas of strong luminescence have been observed in YBCO and BSCCO pellets as well as BSCCO thin films. At low beam energies, there is some correlation between the CL and secondary electron images. The CL spectra of the strongly luminescent spots differed from those of the poorly luminescencing superconducting phases. CL was able to identify a copper-rich impurity phase in the BSCCO material, and a barium cuprate phase in the YBCO material. It is proposed that the quality of a thin film, with respect to impurities, can be monitored using CL.

Ion beam deposition of alumina for recording head applications

In this work, aluminum oxide films were prepared by Ion Beam Deposition (IBD) in a dual-gun system. Films prepared from alumina target at high deposition beam parameters and low assist parameters resulted in lower compressive stress and better etch resistance than sputtered alumina films. Excellent thickness uniformity and topological step coverage were also achieved. Nano-crystalline alumina films with superior etch resistance were grown by reactive sputtering from an aluminum target at low deposition rate. Appropriate balance between the deposition beam and assist beam was important in order to get such high etch resistance. Discussions of both IBD and sputtering methods, the effect of beam parameters on the alumina properties, and structural analysis were presented in this paper.