Stony Brook University, Stony Brook, USA
BNL, Upton, Long Island, New York, USA
A 112MHz superconducting quarter-wave resonator electron gun will be used as the injector of the Coherent Electron Cooling (CEC) proof-of-principle experiment at BNL. Furthermore, this electron gun can be the testing cavity for various photocathodes. In this paper, we present the design of the Fundamental Power Coupler (FPC) and the cathode stalks designated to the future experiments. The axial waveguide structure FPC has the properties of tunable coupling factor and small interference to the electron beam output. The optimization of the coupling factor and the location of the FPC are discussed in detail. Two types of cathode stalks are discussed. Special shape of the stalk is applied in order to minimize the RF power loss. The location of cathode plane is also optimized to enable the extraction of low emittance beam.
BNL, Upton, Long Island, New York, USA
Niowave, Inc., Lansing, Michigan, USA
Brookhaven National Laboratory and Niowave, Inc. have designed and fabricated a superconducting 112 MHz quarter-wave resonator (QWR) electron gun. The first cold test of the QWR cryomodule has been completed at Niowave. The paper describes the cryomodule design, presents the cold test results, and outline plans to upgrade the cryomodule. Future experiments include studies of different photocathodes and use for the coherent electron cooling proof-of-principle experiment. Two cathode stalk options, one for multi-alkali photocathodes and the other one for a diamond-amplified photocathode, are discussed.
BNL, Upton, Long Island, New York, USA
AES, Medford, NY, USA
The 703 MHz superconducting gun for the BNL Energy Recovery Linac (ERL) prototype has two fundamental power couplers (FPCs), and each of them will deliver up to 500 kW of CW RF power. In order to prepare the couplers for high power RF service and process multipacting, the FPCs should be conditioned prior to installation into the gun cryomodule. A conditioning cart based test stand, which includes a vacuum pumping system, controllable bake-out system, diagnostics, interlocks and data log system has been designed, constructed and commissioned by collaboration of BNL and AES. This paper presents FPC conditioning cart systems and the conditioning process.
BNL, Upton, Long Island, New York, USA
The Superconducting Quarter Wave Resonator (QWR) was developed first for heavy ion acceleration in 1981 and became highly successful and widespread in low β linacs. Recently the QWR has been adapted for a variety of applications for high particle velocity, near β=1. The applications are varied, from the use in a relativistic hadron storage ring, to photocathode electron guns and crab cavities. In this work I will describe these applications, and how they benefit from the rather unique properties of this resonator, such as the Higher Order Mode spectrum, the electro-mechanical stability and the compact size.
BNL, Upton, Long Island, New York, USA
To prevent significant loss of the luminosity due to large crossing angle in the future ERL based Electron Ion Collider at BNL (eRHIC), there is a demand for crab cavities. In this article, we will present a novel design of the deflecting/crabbing 200 MHz superconducting RF cavity that will fulfill the requirements of eRHIC. The quarter-wave resonator structure of the new cavity possesses many advantages, such as compact size, high Rt/Q, the absence of same order mode and lower order mode, and easy higher order mode damping. We will present the properties and characteristics of the new cavity in detail.