Search

The recently developed new simplified design for the 400 MHz LHC crabbing cavity presents attractive properties compared to conventional designs. The proposed approach can be equally compact in both transverse dimensions and allows horizontal as well as vertical deflection of the beam in the collider. The significant modification of the parallel-bar design with the bars merged to the side walls of the cavity gives improved properties, such as better mode separation and reduced surface fields*. A transverse deflecting voltage of 3 to 5 MV in a single cavity can be expected with the peak surface electric field lower then 50 MV/m and peak magnetic field below 100 mT. This paper presents engineering issues of the proof-of-concept crabbing cavity d esign and discusses the manufacturing techniques. The paper discusses present status of the project including fabrication of the niobium cavity, as well as room temperature and cryogenic testing.

Proceedings of FEL2010, Malmö, Sweden The Naval Postgraduate School (NPS) Beam Physics Laboratory, Niowave, Inc., and The Boeing Company have completed construction of a superconducting 500 MHz quarter-wave gun and photocathode drive laser system. This prototype gun went from conception to initial operation in just under one calendar year. Such rapid progress is due in part to the decision to develop the gun as a prototype, deliberately omitting some features, such as tuners and a cathode loadlock, desired for a linac beam source. This will enable validation of the basic concept for the gun, including high-charge bunch dynamics, as rapidly as possible, with lessons learned applied to the next generation gun. This paper presents results from initial testing of the gun, technical challenges of the prototype design, and improvements that would enhance capabilities in future versions of this novel design.

Working Group I of the 2009 Energy Recovery Linac Workshop focused on high-brightness, high-power electron beam sources for energy recovery linacs (ERLs), and relevant technology such as development of drive lasers. The WG1 summary paper was broken into two parts: DC guns and loadlocks; and RF guns and drive lasers. This was done both to retain more manageable paper sizes, and because SRF guns are in an earlier stage of development than DC guns. This paper describes the advances, concepts, and thoughts for the latter topics presented at the workshop. There are many challenges to the successful operation of SRF guns as high-brightness, high-average-current beam sources. These combine the set of challenges for high-current SRF cavities (fabrication, cleaning and processing, HOM extraction, etc.), with challenges for high-average-current photocathode sources (photocathode fabrication, quantum efficiency and lifetime, drive laser technology, etc.). New challenges also arise from this combination, such as the requirement for having removable cathodes in an SRF cavity. Practical approaches have been, and are currently being, found to address the problems, and the base of knowledge and experience continues to grow. Alternate ideas are also beginning to make inroads. Hybrid DC-SRF guns, pioneered by Peking University, offer promise for combining the best features of both technologies. Quarter-wave SRF cavities offer compact size for a given frequency, potentially easier fabrication than elliptical cells, and very high transit-time factors for quasi-DC operation. Also, the use of normal-conducting cavities, usually dismissed out of hand due to the required RF power consumption, may become practical with advanced cavity designs. This paper summarizes the state-of-the-art of drive lasers, cathode development and RF gun-based injectors for ERL beam sources The focus in the field has been on DC and SRF guns to date, but interesting approaches for hybrid DC/SRF guns and normal-conducting RF guns are also presented. The paper concludes with discussions of operational issues and concerns, technical issues related to beam source realization, and future concepts.