A new type of bunch compressor and seeding of a short-wavelength coherent radiation.

Abstract

Transverse-to-longitudinal emittance exchange was proposed in [1] as a tool for an effective matching of the electron beam phase space to requirements of a possible application.Here we propose a new purpose, namely, use of two consecutive emittance exchanges equipped with the telescope between them for a bunch compression that can be done without the energy chirp in the electron bunch. In principle it allows to reduce the electron peak current in the linac by moving the bunch compressor to the end of the linac and, thus, to relax collective effects associated with high peak currents. It is also possible to have a split-action compression when the first part is done inside the low-energy part of the linac and the second and final part is done after the linac. We also demonstrate how proposed bunch compressor can be used for frequency upconversion of the energy modulation provided by the laser interacting with the electron beam and thus can prepare a significantly higher frequency seed for seeded free-electron lasers. The same approach can be used for a frequency down-conversion that can be useful for generation of THz radiation.PACS numbers 41.60.Cr, 42.55.Vc 2

Precision Control of the Electron Longitudinal Bunch Shape Using an Emittance-Exchange Beam Line

“…Previous researchers have studied several different types of linear perturbations that arise in the EEX beamline and have proposed several methods to suppress them [14,25,39]. In our previous theoretical work [30], we derived analytic expressions for both linear and nonlinear perturbations and, further, we developed a new method to suppress them termed the "slope-control method".…”

“…These include, superradiant radiation [11][12][13], beam quality control for high brightness beam [14][15][16][17][18], seeding techniques to enhance the performances of X-ray free electron laser [19][20][21], and improving efficiency of ultra-high gradient wakefield accelerations [22][23][24].…”

“…An experiment is planned that will use this beamline to create a drive and witness beam and make them pass through a dielectric structure with a small aperture to achieve high transformer ratio [37]. The only limitation of this beamline is that the final horizontal emittance is large (due to the initial longitudinal emittance) but this can be overcome with a double EEX beamline [14].…”

Electron-beam manipulation techniques in the SINBAD Linac for external injection in plasma wake-field acceleration

“…It is well known that the momentum compaction of a magnetic lattice affects the arrival time jitter of the beam possibly leading to the compression or the compensation of the arrival time jitter [31][32][33].…”

Emittance and phase space exchange for advanced beam manipulation and diagnostics

“…Using a simple rf cavity in the fundamental mode with R 43 ¼ Àk 2 L c =6 to cancel the longitudinal acceleration in the transverse cavity [R 43 in Eq. (8)] allows, to the first order, exact EEX when the thicklens effect of the transverse cavity is taken into account [15].…”