arXiv subjects

H. T. Edwards

Publications and source records attributed to H. T. Edwards.

2 recordsLinked to original sources

arXiv2000

Compression of High-Charge Electron Bunches

The A0 Photoinjector at Fermilab can produce high charge (10-14 nC) electron bunches of low emittance (20 pi mm-mrad for 12 nC). We have undertaken a study of the optimal compression conditions. Off-crest acceleration in the 9-cell capture cavity induces an energy-time correlation, which is rotated by the compressor chicane (4 dipoles). The bunch length is measured using streak camera images of optical transition radiation. We present measurements under various conditions, including the effect of the laser pulse length (2 ps sigma Gaussian vs. 10 ps FWHM flat top). The best compression to date is for a 13.2 nC bunch with sigma = 0.63 mm (1.89 ps), which corresponds to a peak current of 2.8 kA.

physics.acc-ph↗

arXiv2000

Electro-Optic Sampling of Transient Fields from the passage of High-Charge Electron Bunches

When a relativistic electron bunch traverses a structure, strong electric fields are induced in its wake. We present measurements of the electric field as a function of time as measured at a fixed location in the beam line. For a 12 nC bunch of duration 4.2 ps FWHM, the peak field is measured >0.5 MV/m. Time resolution of ~5 ps is achieved using electro-optic sampling with a lithium tantalate (LiTaO_3) crystal and a short-pulse infrared laser synchronized to the beam. We present measurements under several different experimental conditions and discuss the influence of mode excitation in the structure.

physics.acc-ph↗