HZB, Berlin, Germany
JLAB, Newport News, Virginia, USA
NCBJ, Świerk/Otwock, Poland
BNL, Upton, Long Island, New York, USA
DESY, Hamburg, Germany
BINP SB RAS, Novosibirsk, Russia
MBI, Berlin, Germany
FZJ, Jülich, Germany
*T. Kamps et al., Proceedings of the 2nd International Particle Accelerator Conference, San Sebastián, Spain, 2011.
HZDR, Dresden, Germany
JLAB, Newport News, Virginia, USA
In order to improve the gradient of the cavity and the beam quality of the gun, a new design for the SRF photo injector at the Helmholtz-Zentrum Dresden-Rossendorf has been developed. Apart from the special design of the cavity itself – as presented at SRF09, Berlin – the next update will include a separation of input and output of the liquid nitrogen supply system. This is supposed to increase the stability of the nitrogen pressure and enable a better monitoring of its temperature. The implementation of a superconducting solenoid inside the cryomodule is another major improvement. The position of this solenoid can be adjusted with a high precision using two independent step motors, which are thermally isolated from the solenoid itself. The poster will present the progress of turning the first design models into reality.
HZDR, Dresden, Germany
JLAB, Newport News, Virginia, USA
MBI, Berlin, Germany
A lot of the future electron accelerator projects such like ERLs, high power FELs and also some of the new collider designs rely on the development of particle sources which provide them with high average beam currents at high repetition rates, while maintaining a low emittance. SRF photo injectors represent a promising concept to give just that, offering the option of a continuous wave operation with high bunch charges. Nevertheless, emittance compensation for these electron guns, with the goal to reach the same level as normal conducting sources, is an ongoing challenge. The poster is going to discuss several approaches for the 3-1/2-cell SRF gun installed at the accelerator facility ELBE at the Helmholtz Center Dresden-Rossendorf including the installation of a superconducting solenoid within the injector’s cryostat and present the currently used method to determine the beam’s phase space.
JLAB, Newport News, Virginia, USA
Most of the current R&D in SRF is focused on ways to reduce the construction and operating cost of SRF-based accelerators as well as on the development of new or improved cavity processing techniques. The increase in quality factors is the result of the reduction of the surface resistance of the materials. A recent test [*] on a 1.5 GHz single cell cavity made from ingot niobium of medium purity and heat treated at 1400 C in a ultra-high vacuum induction furnace resulted in a residual resistance of ~ 1nanoohm and a quality factor increasing with field up to ~ 5×1010 at a peak magnetic field of 90 mT. In this contribution, we present some results on the investigation of the origin of the extended Q0-increase, obtained by multiple HF rinses, oxypolishing and heat treatment of “all Nb” cavities.
[*] P. Dhakal et al., Phys. Rev. ST Accel. Beams 16, 042001 (2013).
Bergische Universität Wuppertal, Wuppertal, Germany
JLAB, Newport News, Virginia, USA
Enhanced field emission (EFE) from particulate contaminations and surface irregularities is one of the main field limitations of the superconducting Nb cavities required for XFEL and ILC. While the number density of particulate emitters can be reduced by dry ice cleaning (DIC) and clean room assembly, the optimum choice of crystallinity and polishing are still under discussion [1]. For the future ILC cavities, large or even single crystal Nb with a combination of BCP and EP is considered. Therefore, we have systematically investigated the EFE of single crystal Nb samples which got the same total polishing depth 136-138 μm but a different EP/BCP ratio (5.80, 2.40, 0.73, 0.15) and DIC by means of correlated optical/AFM profilometry, field emission scaning microscopy (FESM) and high-resolution SEM. Depending on the surface roughness (Ra < 200 nm), field enhancement factors b of 12 – 42 and emitting areas S up to 0.1 μm² were obtained. High current conditioning (μA - mA) of these emitters usually resulted in a slight reduction of b (factor < 2) but a strong increase of S. The influence of the surface roughness on the EFE and conditioning of the remaining emitters will be discussed.
[1] Reschke et al., Phys. Rev. ST Accel. Beams 13, 071001-1 (2010)
WEIOC03
ANL, Argonne, USA
JLAB, Newport News, Virginia, USA
Fermilab, Batavia, USA
IIT, Chicago, Illinois, USA
I will present a summary of the work done over the last 2 years that encompasses both coupons study of thin superconducting films and multilayers and preliminary superconducting RF cavity tests coated by ALD. I will also present results of Nb onto Copper.
THP014
JLAB, Newport News, Virginia, USA
Compact, high brilliance X-ray sources, based on inverse Compton scattering (ICS), have gained enormous interest worldwide. A compact and affordable superconducting (SC) linac is one of the key components of such applications. JLab is developing the concept of a compact cryostat, which contains two elliptical, 400MHz, 3-cell cavities, to demonstrate the SRF technology for ICS application. In this paper, the RF optimization, HOM criteria, mechanical analysis, fabrication experience and the test result of the prototype cavity are reported.