BNL, Upton, Long Island, New York, USA
BNL, Upton, Long Island, New York, USA
We propose a new method to generate ultra-short x-ray pulses using focused short low energy (5-10MeV) electron bunch to slice a short electron bunch from the electron bunches in a synchrotron radiation storage ring. When the low energy electron bunch crosses from top the high energy electron bunch at right angle, its coulomb force will kick a short slice of high energy electrons away from the core of the storage ring electron bunch. When the low energy electron bunch (about 50 pC) is focused to about 50 micron size and compressed to about 150fs bunch length and is positioned on top of the high energy electron bunch by a distance about 30 micron, the coulomb force is sufficient to give a kick vertically to the electrons within a short slice of the storage ring bunch about 200 fs long with a deflection about 4 micro-radian. This is sufficient to deflect the slice away from the core by a separation of 5 times the angular divergence of the beam. The separated slice when passing through an undulator, will radiate ulstra-short x-ray pulses at about 200 fs. We discuss the advantages and challenges of this new method. We provide data to demonstrate the feasibility of this method.
BNL, Upton, Long Island, New York, USA
Following the proposal of electron beam slicing method to generate short x-ray pulses in storage ring, we studied the feasibility of the crucial technique required by electron beam slicing, i.e., the generation of very low energy electron beam with very small beam size (30 μm) and very short bunch length (100 fs). Based on one of the BNL RF gun, 5 MeV beam energy and 50 pC bunch charge was assumed in the study. The beam ‘natural’ energy-time negative chirp, due to space charge effect, was used and the bunch length is compressed from from 0.8 ps to ~150 fs with a chicane structure. The system is in the space charge dominated regime. We use the code PARMELA and Generic optimization method for parameters optimization with various strategies to overcome the damaging from the space charge effect. After optimization, the beam transverse size is 50 micron and the bunch length is 150 fs, close to our original specification. In this paper we describe the design and the physical process in the compressor and focus section. The study confirmed the possibility to generate strong focused and compressed very low energy beam in the space charge dominated regime.
BNL, Upton, Long Island, New York, USA
BINP SB RAS, Novosibirsk, Russia