Design of a VHF-band RF photoinjector with megahertz beam repetition rate

Staples, J.; Baptiste, K.; Corlett, J.; Kwiatkowski, S.; Lidia, Steven; Qiang, Ji; Sannibale, F.; Sonnad, K.; Virostek, Steve; Wells, R.

doi:10.1109/pac.2007.4440644

Cited by 5 publications

(5 citation statements)

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“…The successful normal-conducting (NC) high-frequency ( * 1 GHz) high-brightness technology used in present low repetition rate x-ray FEL rf guns [12] cannot be scaled to repetition rates beyond $10 kHz because the heat load due to Ohmic losses in the gun cavity becomes too large for being dissipated by the cooling system [13]. Many groups around the world are actively working on alternative electron gun schemes and technologies to achieve the required brightness at high repetition rates [14].…”

Section: Introductionmentioning

confidence: 99%

Advanced photoinjector experiment photogun commissioning results

Sannibale¹,

Filippetto²,

Papadopoulos³

et al. 2012

Phys. Rev. ST Accel. Beams

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The Advanced Photoinjector Experiment (APEX) at the Lawrence Berkeley National Laboratory is dedicated to the development of a high-brightness high-repetition rate (MHz-class) electron injector for x-ray free-electron laser (FEL) and other applications where high repetition rates and high brightness are simultaneously required. The injector is based on a new concept rf gun utilizing a normal-conducting (NC) cavity resonating in the VHF band at 186 MHz, and operating in continuous wave (cw) mode in conjunction with high quantum efficiency photocathodes capable of delivering the required charge at MHz repetition rates with available laser technology. The APEX activities are staged in three phases. In phase 0, the NC cw gun is built and tested to demonstrate the major milestones to validate the gun design and performance. Also, starting in phase 0 and continuing in phase I, different photocathodes are tested at the gun energy and at full repetition rate for validating candidate materials to operate in a high-repetition rate FEL. In phase II, a room-temperature pulsed linac is added for accelerating the beam at several tens of MeV to reduce space charge effects and allow the measurement of the brightness of the beam from the gun when integrated in an injector scheme. The installation of the phase 0 beam line and the commissioning of the VHF gun are completed, phase I components are under fabrication, and initial design and specification of components and layout for phase II are under way. This paper presents the phase 0 commissioning results with emphasis on the experimental milestones that have successfully demonstrated the APEX gun capability of operating at the required performance.

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Section: Introductionmentioning

confidence: 99%

Advanced photoinjector experiment photogun commissioning results

Sannibale¹,

Filippetto²,

Papadopoulos³

et al. 2012

Phys. Rev. ST Accel. Beams

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“…Niowave will design the SRF booster cryomodule in consultation with LBNL's accelerator physicists. LBNL is developing the front-end of the linac based on a copper radio frequency DE-FG02-07ER84882 Topic 15-c 4 of 24 (RF) gun that accelerates the electron beam to 750 keV followed by the SRF multi-cell cavities that will accelerate the beam to 20 MeV [5]. The average beam current for the injector system is 1 mA with plans for high charge operation, 1 nC at 1 MHz, and high brightness operation, 100 pC at 1 MHz.…”

Section: B Identification and Significance Of Opportunity And Technimentioning

confidence: 99%

Development of a CW Superconducting RF Booster Cryomodule for Future Light Sources

Grimm¹,

Bogle²,

Deimling³

et al. 2009

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Future light sources based on seeded free electron lasers (FEL) have the potential to increase the soft xray flux by several orders of magnitude with short bunch lengths to probe electron structure and dynamics. A low emittance, high rep-rate radio frequency (RF) photocathode electron gun will generate the electron beam that will require very stringent beam control and manipulation through the superconducting linear accelerator to maintain the high brightness required for an x-ray FEL. The initial or booster cavities of the superconducting radio frequency (SRF) linear accelerator will require stringent control of transverse kicks and higher order modes (HOM) during the beam manipulation and conditioning that is needed for emittance exchange and bunch compression. This SBIR proposal will develop, fabricate and test a continuous-wave SRF booster cryomodule specifically for this application. Phase I demonstrated the technical feasibility of the project by completing the preliminary SRF cavity and cryomodule design and its integration into an R&D test stand for beam studies at Lawrence Berkeley National Laboratory (LBNL). The five-cell bulk niobium cavities operate at 750 MHz, and generate 10 MV each with strong HOM damping and special care to eliminate transverse kicks due to couplers. Due to continuous-wave operation at fairly modest beam currents and accelerating gradients the complexity of the two cavity cryomodule is greatly reduced compared to an ILC type system. Phase II will finalize the design, and fabricate and test the booster cryomodule. The cryomodule consists of two five-cell cavities that will accelerate megahertz bunch trains with nano-coulomb charge. The accelerating gradient is a very modest 10 MV/m with peak surface fields of 20 MV/m and 42.6 mT. The cryogenic system operates at 2 K with a design dynamic load of 20 W and total required cryogenic capacity of 45 W. The average beam current of up to 1 mA corresponds to a beam power of 10 kW per 5cell cavity and will require 20 kW of RF power for transmission, control and regulation. The RF power will be supplied by a commercial tetrode. Cryogenic tests will be carried out at LBNL to make use of their test facilities, cryogenics and laser systems, and for future use with beam. Demonstration of this new type of booster cryomodule will open many new applications of SRF linear accelerators. Niowave Inc.

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“…We are developing a design for a high-brightness, high-repetition-rate electron gun that uses a normal-conducting rf structure in the very-high-frequency (VHF) range, at approximately 100 MHz [12]. The gun cavity has quarter-wave coaxial geometry, which is a mature rf technology.…”

Section: Vhf Photo Gunmentioning

confidence: 99%