IPAC2016 - List of Authors (Schreiber, S.)

Paper	Title	Page
MOPOW010	The Superconducting Soft X-ray Free-Electron Laser User Facility FLASH	729
	M. Vogt, J. Feldhaus, K. Honkavaara, J. Rönsch-Schulenburg, S. Schreiber, R. Treusch DESY, Hamburg, Germany
	FLASH, the superconducting free-electron laser at DESY delivers up to several thousand photon pulses per second with wavelengths ranging from 52 nm down to as low as 4.2 nm and with pulse energies of up to 500 uJ to photon users at the FLASH1 beamline. In 2014 and 2015 a second beamline, FLASH2, has been commissioned in parallel to user operation at FLASH1. FLASH produces bunch trains of up to 800 bunches in 0.8 ms with a train repetition rate of 10 Hz. Each train can be split in sub-trains for FLASH1 and FLASH2, such that both beamlines receive bursts of bunches with full 10 Hz. Operational highlights are the latest SASE energy record of 600 uJ at 15 nm in FLASH2, and the first simultaneous SASE lasing of three undulator systems: FLASH1 (13.7 nm), sFLASH (38 nm), and FLASH2 (20 nm). sFLASH is the seeding experiment in the FLASH1 beamline. Moreover we will report on recent technical and operational improvements. A major success is the improved reliability and stability of the whole facility with shorter SASE tuning times.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW010
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MOPOW011	Operation of Free Electron Laser FLASH Driven by Short Electron Pulses	732
	V. Balandin, G. Brenner, C. Gerth, N. Golubeva, U. Mavrič, H. Schlarb, E. Schneidmiller, S. Schreiber, B. Steffen, M. Yan, M.V. Yurkov DESY, Hamburg, Germany E. Hass, A. Kuhl, T. Plath, M. Rehders, J. Rönsch-Schulenburg, J. Roßbach University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
	The program of low charge mode of operation is under development at free electron laser FLASH aiming in single mode radiation pulses. A short pulse photoinjector laser has been installed at FLASH allowing production of ultrashort electron pluses with moderate compression factor of the beam formation system. Here we present pilot results of free electron laser FLASH operating at the wavelength of 13.1 nm and driven by 70 pC electron bunches. Relevant theoretical analysis has been performed showing good agreement with experimental results.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW011
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MOPOW014	Measurements of Ultrasmall Charges with MCP Detector in FLASH Accelerator	741
	O.I. Brovko, A.Yu. Grebentsov, A.V. Shabunov, E. Syresin JINR, Dubna, Moscow Region, Russia S. Schreiber, M.V. Yurkov DESY, Hamburg, Germany
	Structure of the dark current passed through the undulator is a matter of great concern. Two effects can contribute to the dark current: emission of electrons from "hot" spots in the gun, and generation of "ghost" bunches due to possible leakage of the photoinjector laser. MCP based photon detector has been used for measurements of radiation energy from electron bunch. For small radiation densities the light is detected by direct illumination of the MCP plate, and for large densities a small angle scattering scheme is realized when metallic mesh scatters tiny fraction of light on the MCP plate. In the present experiment we used geometry of direct illumination of MCP plate aiming detection of "ghost" bunches which may generate parasitically from the laser driven electron gun. Reduction of background conditions allowed us to detect light produced by electron bunches with extremely small charges, down to a few femtocoulmb. We measured for the first time structure of the dark current passing through the FLASH undulator. We have also been able to measure a high contrast of radiation produced by the photoinjector laser pulses switched on and off by a 1 MHz repetition rate Pockels cells.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW014
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Paper

Title

Page

The Superconducting Soft X-ray Free-Electron Laser User Facility FLASH

729

M. Vogt, J. Feldhaus, K. Honkavaara, J. Rönsch-Schulenburg, S. Schreiber, R. Treusch
DESY, Hamburg, Germany

FLASH, the superconducting free-electron laser at DESY delivers up to several thousand photon pulses per second with wavelengths ranging from 52 nm down to as low as 4.2 nm and with pulse energies of up to 500 uJ to photon users at the FLASH1 beamline. In 2014 and 2015 a second beamline, FLASH2, has been commissioned in parallel to user operation at FLASH1. FLASH produces bunch trains of up to 800 bunches in 0.8 ms with a train repetition rate of 10 Hz. Each train can be split in sub-trains for FLASH1 and FLASH2, such that both beamlines receive bursts of bunches with full 10 Hz. Operational highlights are the latest SASE energy record of 600 uJ at 15 nm in FLASH2, and the first simultaneous SASE lasing of three undulator systems: FLASH1 (13.7 nm), sFLASH (38 nm), and FLASH2 (20 nm). sFLASH is the seeding experiment in the FLASH1 beamline. Moreover we will report on recent technical and operational improvements. A major success is the improved reliability and stability of the whole facility with shorter SASE tuning times.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW010

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reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPOW011

Operation of Free Electron Laser FLASH Driven by Short Electron Pulses

732

V. Balandin, G. Brenner, C. Gerth, N. Golubeva, U. Mavrič, H. Schlarb, E. Schneidmiller, S. Schreiber, B. Steffen, M. Yan, M.V. Yurkov
DESY, Hamburg, Germany
E. Hass, A. Kuhl, T. Plath, M. Rehders, J. Rönsch-Schulenburg, J. Roßbach
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

The program of low charge mode of operation is under development at free electron laser FLASH aiming in single mode radiation pulses. A short pulse photoinjector laser has been installed at FLASH allowing production of ultrashort electron pluses with moderate compression factor of the beam formation system. Here we present pilot results of free electron laser FLASH operating at the wavelength of 13.1 nm and driven by 70 pC electron bunches. Relevant theoretical analysis has been performed showing good agreement with experimental results.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW011

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MOPOW014

Measurements of Ultrasmall Charges with MCP Detector in FLASH Accelerator

741

O.I. Brovko, A.Yu. Grebentsov, A.V. Shabunov, E. Syresin
JINR, Dubna, Moscow Region, Russia
S. Schreiber, M.V. Yurkov
DESY, Hamburg, Germany

Structure of the dark current passed through the undulator is a matter of great concern. Two effects can contribute to the dark current: emission of electrons from "hot" spots in the gun, and generation of "ghost" bunches due to possible leakage of the photoinjector laser. MCP based photon detector has been used for measurements of radiation energy from electron bunch. For small radiation densities the light is detected by direct illumination of the MCP plate, and for large densities a small angle scattering scheme is realized when metallic mesh scatters tiny fraction of light on the MCP plate. In the present experiment we used geometry of direct illumination of MCP plate aiming detection of "ghost" bunches which may generate parasitically from the laser driven electron gun. Reduction of background conditions allowed us to detect light produced by electron bunches with extremely small charges, down to a few femtocoulmb. We measured for the first time structure of the dark current passing through the FLASH undulator. We have also been able to measure a high contrast of radiation produced by the photoinjector laser pulses switched on and off by a 1 MHz repetition rate Pockels cells.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW014

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