  Investigations of the laser-induced microbunching as it is related to
time-sliced electron-beam diagnostics and high-gain-harmonic generation (HGHG)
free-electron lasers using bright electron beams are proposed for the ASTA
facility. Initial tests at 40-50 MeV with an amplified 800-nm seed laser beam
co-propagating with the electron beam through a short undulator (or modulator)
tuned for the resonance condition followed by transport through a subsequent
chicane will result in energy modulation and z-density modulation
(microbunching), respectively. The latter microbunching will result in
generation of coherent optical or UV transition radiation (COTR, CUVTR) at a
metal converter screen which can reveal slice beam size, centroid, and energy
spread. Additionally, direct assessment of the microbunching factors related to
HGHG by measurement of the COTR intensity and harmonic content after the
chicane as a function of seed laser power and beam parameters will be done.
These experiments will be performed using the ASTA 3-MHz-rate micropulse train
for up to 1ms which is unique to test facilities in the USA.
