FEL2013 - List of Authors (Ziemann, V.G.)

Paper

Title

Page

Status of the EU-XFELl Laser Heater

271

M. Hamberg, V.G. Ziemann
Uppsala University, Uppsala, Sweden

Funding: This work was supported by the Swedish Research Council under contract number DNR-828-2008-1093.
We describe the technical layout and the status of the laser heater system for the EuXFEL. The laser heater is needed to increase the momentum spread of the electron beam to prevent micro-bunching instabilities in the linac.

WEOANO03

Longitudinal Coherence in an FEL With a Reduced Level of Shot Noise

469

V.A. Goryashko
Private Address, Uppsala, Sweden
V.G. Ziemann
Uppsala University, Uppsala, Sweden

For a planar free electron laser (FEL) configuration we study self-amplified coherent spontaneous emission driven by a gradient of the bunch current in the presence of different levels of noise in bunches [1]. We calculate the probability density distribution of the maximum power of the radiation pulses for different levels of shot noise. It turns out that the temporal coherence quickly increases as the noise level reduces. We also show that the FEL based on coherent spontaneous emission produces almost Fourier transform limited pulses and the time-bandwidth product is mainly determined by the bunch length and the interaction distance in an undulator. We also propose a scheme that permits the formation of electron bunches with a reduced level of noise and a high gradient of the current at the bunch tail to enhance coherent spontaneous emission. The presented scheme uses effects of noise reduction and controlled microbunching instability and consists of a laser heater, a bunch compressor, and a shot noise suppression section. The noise factor and microbunching gain of the overall proposed scheme with and without laser heater are estimated.
V.A. Goryashko and V. Ziemann, Phys. Rev. ST Accel. Beams 16, 030702 (2013).

Slides WEOANO03 [1.999 MB]

Paper	Title	Page
TUPSO25	Status of the EU-XFELl Laser Heater	271
	M. Hamberg, V.G. Ziemann Uppsala University, Uppsala, Sweden
	Funding: This work was supported by the Swedish Research Council under contract number DNR-828-2008-1093. We describe the technical layout and the status of the laser heater system for the EuXFEL. The laser heater is needed to increase the momentum spread of the electron beam to prevent micro-bunching instabilities in the linac.

WEOANO03	Longitudinal Coherence in an FEL With a Reduced Level of Shot Noise	469
	V.A. Goryashko Private Address, Uppsala, Sweden V.G. Ziemann Uppsala University, Uppsala, Sweden
	For a planar free electron laser (FEL) configuration we study self-amplified coherent spontaneous emission driven by a gradient of the bunch current in the presence of different levels of noise in bunches [1]. We calculate the probability density distribution of the maximum power of the radiation pulses for different levels of shot noise. It turns out that the temporal coherence quickly increases as the noise level reduces. We also show that the FEL based on coherent spontaneous emission produces almost Fourier transform limited pulses and the time-bandwidth product is mainly determined by the bunch length and the interaction distance in an undulator. We also propose a scheme that permits the formation of electron bunches with a reduced level of noise and a high gradient of the current at the bunch tail to enhance coherent spontaneous emission. The presented scheme uses effects of noise reduction and controlled microbunching instability and consists of a laser heater, a bunch compressor, and a shot noise suppression section. The noise factor and microbunching gain of the overall proposed scheme with and without laser heater are estimated. V.A. Goryashko and V. Ziemann, Phys. Rev. ST Accel. Beams 16, 030702 (2013).
	Slides WEOANO03 [1.999 MB]