IPAC2011 - List of Authors (Goryashko, V.A.)

Paper	Title	Page
THPC097	Transverse Alignment Tolerances for the European XFEL Laser Heater	3116
	V.A. Goryashko NASU/IRE, Kharkov, Ukraine M. Dohlus DESY, Hamburg, Germany M. Hamberg, V.G. Ziemann Uppsala University, Uppsala, Sweden
	Funding: Supported by the KTH-SU-UU FEL Center. We study the impact of misalignments between a laser beam and an electron bunch on the energy distribution function of the electron bunch in the laser heater. Transverse position and angular misalignment as well as different spot size of the laser and electron beam are considered. We find that the transverse misalignment makes the energy distribution function narrower compared to the case of ideal adjustment and a distinct peak in the distribution around the initial mean value of the energy appears. We demonstrate that despite these misalignments a uniform heating in terms of the energy spread can be achieved by appropriately adapting the transverse size and power of the laser beam such that the energy distribution function of the electron bunch at the end of the laser heater can be made similar to a Gaussian, thus providing more effective Landau damping against the micro-bunching instability. The laser power mainly determines the local energy spread while the laser spot size governs the shape of the energy distribution function. The transverse oscillations of electrons induced by the magnetic field in the laser heater are found to be non-essential for typical operation parameters.

Paper

Title

Page

Transverse Alignment Tolerances for the European XFEL Laser Heater

3116

V.A. Goryashko
NASU/IRE, Kharkov, Ukraine
M. Dohlus
DESY, Hamburg, Germany
M. Hamberg, V.G. Ziemann
Uppsala University, Uppsala, Sweden

Funding: Supported by the KTH-SU-UU FEL Center.
We study the impact of misalignments between a laser beam and an electron bunch on the energy distribution function of the electron bunch in the laser heater. Transverse position and angular misalignment as well as different spot size of the laser and electron beam are considered. We find that the transverse misalignment makes the energy distribution function narrower compared to the case of ideal adjustment and a distinct peak in the distribution around the initial mean value of the energy appears. We demonstrate that despite these misalignments a uniform heating in terms of the energy spread can be achieved by appropriately adapting the transverse size and power of the laser beam such that the energy distribution function of the electron bunch at the end of the laser heater can be made similar to a Gaussian, thus providing more effective Landau damping against the micro-bunching instability. The laser power mainly determines the local energy spread while the laser spot size governs the shape of the energy distribution function. The transverse oscillations of electrons induced by the magnetic field in the laser heater are found to be non-essential for typical operation parameters.