Marek Otevrel

Transverse emittance is one of the most important properties for high-brightness electron beams used for X-Ray free-electron lasers. The photo injector test facility at DESY in Zeuthen (PITZ) focuses on the development of high-brightness electron sources. The two main methods to measure the emittance are the quadrupole scan and the slit scan. Combining either of these methods with a transverse deflecting cavity allows the measurement of the slice emittance. At PITZ, space-charge effects at the low beam momentum of 24 MeV/c complicate in particular the quadrupole scan. This has to be considered in the emittance measurements. First slit-scan based slice emittance results will be shown next to studies on the beam transport for quadrupole scans.

Recently three RF guns were prepared at the Photo Injector Test Facility at DESY, location Zeuthen (PITZ) for their subsequent operation at FLASH and the European XFEL. The gun 3.1 is a previous cavity design and is currently installed and operated at FLASH, the other two guns 4.3 and 4.4 were of the current cavity design and are dedicated to serve for the start-up of the European XFEL photo-injector. All three cavities had been dry-ice-cleaned prior their conditioning and hence showed low dark current levels. The lowest dark current level – as low as 60μA at 65MV/m field amplitude – has been observed for the gun 3.1. This paper reports in details about the conditioning process of the most recent gun 4.4. It informs about experience gained at PITZ during establishing of the RF conditioning procedure and provides a comparison with the other gun cavities in terms of the dark currents. It also summarizes the major setup upgrades, which have affected the conditioning processes of the ca...

A new concept for electrospray coupling of microfluidic devices with mass spectrometry was developed. The sampling orifice of the time-of-flight mass spectrometer was modified with an external adapter assisting in formation and transport of the electrosprayed plume from the multichannel polycarbonate microdevice. The compact disk sized microdevice was designed with radial channels extending to the circumference of the disk. The electrospray exit ports were formed by the channel openings on the surface of the disk rim. No additional tips at the channel exits were used. Electrospray was initiated directly from the channel openings by applying high voltage between sample wells and the entrance of the external adapter. The formation of the spatially unstable droplet at the electrospray openings was eliminated by air suction provided by a pump connected to the external adapter. Compared with the air intake through the original mass spectrometer sampling orifice, more than an order of magnitude higher flow rate was achieved for efficient transport of the electrospray plume into the mass spectrometer. Additional experiments with electric potentials applied between the entrance sections of the external adapter and the mass spectrometer indicated that the air flow was the dominant transport mechanism. Basic properties of the system were tested using mathematical modeling and characterized using ESI/TOF-MS measurements of peptide and protein samples.

The main goal of the Photo Injector Test facility at DESY, Zeuthen site, (PITZ) is the development, optimization and detailed characterization of electron sources for short wavelength Free Electron Lasers (FELs) like FLASH and the European XFEL. For a successful operation of such type of FELs the injector must produce high quality electron bunches, short enough in duration with high charge and small transverse emittance value. Installation of the Transverse Deflecting Structure (TDS) at PITZ will provide the possibility for detailed characterization of the bunch temporal profile, bunch transverse slice emittance and longitudinal phase space. The TDS cavity is currently installed at PITZ beamline, and commissioning of the whole TDS system is expected in the spring-summer 2012. In the first part of the paper the PITZ2.0 setup is shortly described. The basic principles of the TDS deflector are introduced. The temporal resolution is discussed. Systematic limitations are estimated. Simul...

In the present work the Booster Cavity Simulation in Photo Injector Test Facility at DESY, Zeuthen site (PITZ) was performed. The main purpose of these simulations was to obtain a simplified model of the booster cavity which should be used later during development of the automatic procedure of optimizing the electron beam trajectory through the booster. I used the V-Code (a beam dynamic simulation program which implements the momentum approach of the beam) for obtaining the trajectories for different input parameters. A method for analysis of the simulated data was suggested. The simulated data were used to make multidimensional Legendre expansions of the output parameters (position and deflection of the beam center of mass at the end of the booster) as the function of the input parameters (beam position and deflection at the input and field phase).

ABSTRACT The Photo Injector Test facility at DESY, Zeuthen site (PITZ), has been designed and built to be a test stand for photo injectors of linac based free-electron lasers. Several diagnostic systems are used to study and optimize electron sources for the Free-electron LASer in Hamburg (FLASH) and the European x-ray free-electron laser (European XFEL). Characterization and experimental results from the last run period showed that gun operation with an average RF power of 50 kW was achieved. This corresponds to a peak power level of 7 MW, >700 s RF pulse length and a repetition rate of 10 Hz. The minimum measured geometric mean of the normalized projected rms emittance in both transverse directions was 0.89 mm-mrad for 1 nC bunch charge. This value shows that the required normalized transverse projected emittance for the photoinjector of the European XFEL can be realized at PITZ. Overview of components and diagnostics as well as some experimental results will be presented. Keywords: free-electron laser, photo injector, photocathode RF-gun, electron beam diagnostics Figure 1. Schematic diagram of the current PITZ beam line including electron gun, booster cavity, dispersive arms (DISP), screen stations and emittance measurement system (EMSY) stations.