DIPAC2011 - List of Keywords (RF-structure)

Paper	Title	Other Keywords	Page
TUPD31	Measurement of the Slice Energy Spread Induced by a Transverse Deflecting RF Structure at FLASH	electron, FEL, emittance, free-electron-laser	371
	C. Gerth, C. Behrens DESY, Hamburg, Germany
	Operation of a high-gain free-electron laser requires a high-brightness electron beam with high peak current and small slice energy spread. The slice energy spread can be measured with high longitudinal resolution by using a transverse deflecting structure in combination with viewing screen in a dispersive section. However, off-axis accelerating fields induce a correlated energy spread that depends inversely proportional on the longitudinal resolution. As a consequence, short bunches, which intrinsically require a high longitudinal resolution in order to be diagnosed, suffer from a large induced energy spread which limits the energy resolution. To be able to measure the impact of the transverse deflecting structure on the slice energy spread without distortions by space charge or coherent synchrotron radiation effects, we tailored short electron bunches with low peak currents by clipping low energy electrons in the collimator of the first bunch compressor at FLASH. In this paper, we present first systematic measurements of the correlated energy spread induced by a transverse deflecting structure. The results are compared with analytical calculations.

Paper

Title

Other Keywords

Page

TUPD31

Measurement of the Slice Energy Spread Induced by a Transverse Deflecting RF Structure at FLASH

electron, FEL, emittance, free-electron-laser

371

C. Gerth, C. Behrens
DESY, Hamburg, Germany

Operation of a high-gain free-electron laser requires a high-brightness electron beam with high peak current and small slice energy spread. The slice energy spread can be measured with high longitudinal resolution by using a transverse deflecting structure in combination with viewing screen in a dispersive section. However, off-axis accelerating fields induce a correlated energy spread that depends inversely proportional on the longitudinal resolution. As a consequence, short bunches, which intrinsically require a high longitudinal resolution in order to be diagnosed, suffer from a large induced energy spread which limits the energy resolution. To be able to measure the impact of the transverse deflecting structure on the slice energy spread without distortions by space charge or coherent synchrotron radiation effects, we tailored short electron bunches with low peak currents by clipping low energy electrons in the collimator of the first bunch compressor at FLASH. In this paper, we present first systematic measurements of the correlated energy spread induced by a transverse deflecting structure. The results are compared with analytical calculations.