360 research outputs found
Generation of Coherent X-Ray Radiation Through Modulation Compression
In this paper, we propose a scheme to generate tunable coherent X-ray
radiation for future light source applications. This scheme uses an energy
chirped electron beam, a laser modulator, a laser chirper and two bunch
compressors to generate a prebunched kilo-Ampere current electron beam from a
few tens Ampere electron beam out of a linac. The initial modulation energy
wavelength can be compressed by a factor of in phase space,
where is the energy bunch length chirp introduced by the laser chirper,
is the momentum compaction factor of the first bunch compressor. As
an illustration, we present an example to generate more than 400 MW, 170
attoseconds pulse, 1 nm coherent X-ray radiation using a 60 Ampere electron
beam out of the linac and 200 nm laser seed. Both the final wavelength and the
radiation pulse length in the proposed scheme are tunable by adjusting the
compression factor and the laser parameters
Stability condition for the drive bunch in a collinear wakefield accelerator
The beam breakup instability of the drive bunch in the structure-based
collinear wakefield accel- erator is considered and a stabilizing method is
proposed. The method includes using the specially designed beam focusing
channel, applying the energy chirp along the electron bunch, and keeping energy
chirp constant during the drive bunch deceleration. A stability condition is
derived that defines the limit on the accelerating field for the witness bunch.Comment: 10 pages, 6 figure
A wide bandwidth free-electron laser with mode locking using current modulation
A new scheme for mode locking a free-electron laser (FEL) amplifier is proposed based on electron beam current modulation. It is found that certain properties of the original concept (Thompson and McNeil 2008 Phys. Rev. Lett. 100 203901), based on the energy modulation of electrons, are improved, including the spectral brightness of the source and the purity of the series of short pulses. Numerical comparisons are made between the new and old schemes and between a mode-locked FEL and a self-amplified spontaneous emission FEL. Illustrative examples using a hypothetical mode-locked FEL amplifier are provided. The ability to generate intense coherent radiation with a large bandwidth is demonstrated
Proposal for an Enhanced Self-Amplified Spontaneous Emission X-ray Free Electron Laser
We describe a technique by which an energy modulation of electrons via interaction with a laser pulse in a wiggler magnet is used for a significant increase of the electron peak current prior to entering a long SASE FEL undulator. This results in a reduction of the gain length for the SASE process and a modification of the structure of the output x-ray radiation. It also temporally links the output x-ray pulse to the initial laser pulse, thus providing an opportunity for accurate synchronization between the laser pump pulse and x-ray probe pulse for pump-probe experiments
- …