Keyword: SRF
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MOPSO76 FEL Operation With the Superconducting RF Photo Gun at ELBE gun, laser, FEL, cavity 136
 
  • J. Teichert, A. Arnold, H. Büttig, M. Justus, U. Lehnert, P.N. Lu, P. Michel, P. Murcek, R. Schurig, W. Seidel, H. Vennekate, R. Xiang
    HZDR, Dresden, Germany
  • T. Kamps, J. Rudolph
    HZB, Berlin, Germany
  • I. Will
    MBI, Berlin, Germany
 
  The superconducting RF photoinjector (SRF gun) operating with a 31/2-cell niobium cavity and Cs2Te photocathodes is installed at the ELBE radiation center. The gun provides beams for ELBE as well as in a separate diagnostics beam line for beam parameter measurements. Since 2012 a new UV driver laser system developed by MBI has been installed for the SRF gun . It delivers CW or bust mode pulses with 13 MHz repetition rate or with reduced rates of 500, 200, and 100 kHz at an average UV power of about 1 W. The new laser allows the gun to serve as the driver for the infrared FELs at ELBE. In the first successful experiment a 250 μA beam with 3.3 MeV from SRF gun was injected into ELBE, further accelerated in the ELBE superconducting linac modules and then guided to the U100 undulator. First lasing was achieved at the wavelength of 41 μm. The spectrum, detuning curve and further parameters were measured.  
 
TUICNO01 Progress in SRF Guns gun, electron, cavity, cathode 176
 
  • S.A. Belomestnykh
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE
In the last couple of years great progress has been made in the commissioning and operation of SRF electron beam sources. Both elliptical cavity designs and reentrant cavities have been developed. This talk will review recent progress in SRF guns.
 
slides icon Slides TUICNO01 [12.748 MB]  
 
TUPSO44 Transverse Emittance Measurement by Slit-scan Method for an SRF Photo Injector emittance, solenoid, background, laser 322
 
  • P.N. Lu, A. Arnold, P. Michel, P. Murcek, J. Teichert, H. Vennekate, R. Xiang
    HZDR, Dresden, Germany
 
  Funding: European Community-Research Infrastructure Activity German Federal Ministry of Education and Research Grant 05 ES4BR1/8, LA³NET funding, Grant Agreement Number GA-ITN-2011-289191
A 3½-cell SRF-gun has been developed and commissioned in Helmholtz-Zentrum Dresden-Rossendorf (HZDR) since 2004. The emittance of this gun was measured before by both solenoid/quadrupole scanning method and multiple slits method. Recently we did new measurements by single slit scanning method which outputs a detailed phase space with higher space resolution and no overlapping problem. This contribution will first describe our diagnostics beam line and software functions, focusing on data processing algorithm. Then an investigation will be presented on the emittance dependence on several important gun parameters as bunch charge, laser phase and DC voltage on the photo cathode. For the bunch charge, a linear increasing relation with the emittance was found. Lower laser phase and higher DC voltage result in lower beam emittance. The influence of a downstream solenoid is studied for the preliminary understanding of the emittance compensation. The contribution will discuss the measurement errors and compare results with other methods. Also, ASTRA simulations of the SRF-gun beams with same parameters will be presented which have similar trends like our measurements.
 
 
TUPSO63 High Average Brightness Photocathode Development for FEL Applications cathode, gun, laser, electron 376
 
  • T. Rao, I. Ben-Zvi, J. Skaritka, E. Wang
    BNL, Upton, Long Island, New York, USA
 
  Next generation, high average flux, light sources call for electron beams with high average current as well as high peak brightness. Alkali antimonide cathodes, especially K2CsSb show great promise in delivering electron beams to meet these requirements. In the past few years, there have been a number of experiments geared towards understanding the stoichiometry, crystalline structure, surface properties and sensitivity of these cathodes. At BNL, we have used the x-ray beams from NSLS, CFN and CHESS for in-situ characterization of K-Cs-Sb cathode growth. We have also designed and built several load-lock systems for ex-situ cathode fabrication and quick cathode exchange, to be used with a number of guns. One load-lock system/cathode combination has been tested with a DC gun and the others will be tested with SRF guns operating at 112 and 704 MHz. In this paper we will present the results on improving the QE with excimer laser and the performance of the load-lock/cathode combination in the guns.  
 
TUPSO92 Dark Current Measurements at the Rossendorf SRF Gun cavity, gun, cathode, electron 455
 
  • R. Xiang, A. Arnold, P.N. Lu, P. Murcek, J. Teichert, H. Vennekate
    HZDR, Dresden, Germany
  • R. Barday, T. Kamps
    HZB, Berlin, Germany
  • V. Volkov
    BINP SB RAS, Novosibirsk, Russia
 
  Funding: the European Community-Research Infrastructure Activity (EuCARD, contract number 227579) and the German Federal Ministry of Education and Research grant 05 ES4BR1/8
In high gradient photo injectors electron field emission creates so-called dark current. The dark current produces beam loss that increases the radiation level, causes damages to the accelerator components, and produces additional background for the users. Field emitted electrons which stay inside the gun, increases RF power consumption and heat load for the superconducting cavities. It is also believed that dark current is the source of local outgassing and plasma formation which can damage sensitive photocathodes. Thus, to understand and control the dark current has become increasingly important for accelerators. In this presentation, we report on dark current measurement at the ELBE SRF Gun at HZDR. The measurements were carried out with the 3.5 cell-cavity SRF gun and Cs2Te photocathodes. We discuss the dark current behavior for different cavity gradients and various solenoid fields. Simulations have been done to understand the experimental results.
 
 
WEPSO31 THz Radiation Source Potential of the R&D ERL at BNL gun, electron, linac, emittance 566
 
  • D. Kayran, I. Ben-Zvi, Y.C. Jing, B. Sheehy
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by BSA DOE, Contract No. DE-AC02-98CH10886
An ampere class 20 MeV superconducting Energy Recovery Linac (ERL) is under commissioning at Brookhaven National Laboratory (BNL) for testing concepts for high-energy electron cooling and electron-ion colliders. This ERL will be used as a test bed to study issues relevant for very high current ERLs. High repetition rate (9.5 MHz), CW operation and high performance of electron beam with some additional components make this ERL an excellent driver for high power coherent THz radiation source*. We discuss potential use of BNL ERL as a source of THz radiation and results of the beam dynamics simulation. We present the status and commissioning progress of the ERL.
*Ilan Ben-Zvi. et al. Coherent harmonic generation of THz radiation using wakefield bunching (presented at this conference)