Andrea Marziali

Feedback stabilization of the SCA/FEL wavelength

Abstract The Stanford superconducting accelerator/free electron laser provides the unique ability to modulate laser wavelength on fast time scales by electronically varying the energy of the electron beam. Through the use of an appropriate feedback circuit, this offers us the opportunity to stabilize the laser wavelength. Our first attempt at frequency response measurement and stabilization is discussed, as are possibilities for future work.

Wavelength shifting in the Stanford FEL

Abstract The time evolution of FEL wavelength in response to small perturbations of the electron energy was measured in the Stanford FEL for a range of operating parameters. The dependence of the wavelength response on the cavity Q , desynchronism, and electron pulse length was also measured. A simple model of the wavelength shifting mechanism is presented which explains the observed behavior.

Demonstration of wavelength stabilization in a free-electron laser

Wavelength stabilization of a free-electron laser (FEL) through the use of negative feedback has been successfully demonstrated at the Stanford Picosecond FEL Center. Short-term wavelength fluctuations have been reduced by-an order of magnitude and drift has been virtually eliminated. >

Microphonic analysis of cryo-module design

Mechanical resonances in superconducting accelerator structures and cryo-module components can lead to coupling between mechanical noise and electron beam parameters. We have studied the mechanical resonance spectrum of a 500 MHz 2-cell structure and cryo-module that was designed and built by Siemens for TRW, Inc., and have measured the effect of these vibrational modes on the RF eigenfrequency of the structure. We identify the most dangerous resonances of this system and discuss related design issues.<<ETX>>