A transition radiation experiment to measure the electron beam modulation induced by the free electron laser: a design study

• Main Author: Joynson, Jack E.
• Other Authors: Buskirk, Fred Ramon
• Language: en_US
• Published: 2012
• Online Access: http://hdl.handle.net/10945/22561

The modulated beam of the free electron laser when passed through a thin target should produce strong transition radiation. The measurement of the transition radiation is a direct measurement of the electron beam modulation in the free electron laser A transition radiation experiment using the Stanford MKIII Infrared Free Electron Laser (IRFEL) has been proposed. The analysis has centered on TRANSPORT, a computer program used for designing charged particle beam systems. The MKIII IRFEL wiggler exit bending magnet system was modeled using TRANSPORT. Analysis reveals that the transverse emittance and momentum spread characteristics will cause the modulated beam to demodulate along the path of the central trajectory. A detector location 10 millimeters downstream of the first bending magnet is found suitable for the measurement of the electron beam modulation. For this case the thin foil must be rotated approximately 11.25 degrees about the y axis to yield a minimum effective picobunch extent as seen by the thin foil. Alternate FEL systems are suggested for investigation