Progress on superconducting rf for the cornell energy-recovery-linac

2007 IEEE Particle Accelerator Conference (PAC), 2007

Six 1300 MHz superconducting niobium 2-cell cavities are manufactured in-house for the prototype of the Cornell ERL injector to boost the energy of a high current, low emittance beam produced by a DC gun. Designed for high current beam acceleration, these cavities have new characteristics as compared to previously developed low-current cavities such as those for TTF. Precision manufacture is emphasized for a better straightness of the cavity axis so as to avoid unwanted emittance dilution. We present the manufacturing, processing and vertical test performance of these cavities. We also present the impact of new cavity characteristics to the cavity performance as learnt from vertical tests.

Presented at, 2012

Cornell University has developed a SCRF injector cryomodule for the acceleration of high current, low emittance beams in continuous wave operation. This cryomodule is based on superconducting RF technology, and is currently under extensive testing in the Cornell ERL injector prototype with CW beam currents exceeding 50 mA. Strong damping of Higher-Order-Modes in the cavities is essential for high beam current operation, and is achieved by beamline RF absorber located at cryogenic temperatures in the beam pipe sections between the cavities. This paper gives an overview of the experience gained during the high beam current operation of the cryomodule.

2010

ERLs have the powerful potential to provide very high current beams with exceptional and tailored parameters for many applications, from next-generation light sources to electron coolers. However, the demands placed on the electron source are severe. It must operate CW, generating a current of 100 mA or more with a normalized emittance of order 1 μm rad. Beyond these requirements, issues such as dark current and long-term reliability are critical to the success of ERL facilities. As part of the BERLinPro project, Helmholtz Zentrum Berlin (HZB) is developing a CW SRF photoinjector in three stages, the first of which is currently being installed at HZB's HoBiCaT facility. It consists of an SRF-cavity with a Pb cathode and a superconducting solenoid. Subsequent development stages include the integration of a high-quantum-efficiency cathode and RF components for high-current operation. This paper discusses the first stage towards an ERL-suitable SRF photoinjector, the present status of the facility and first cavity tests.

2012

eRHIC will collide high-intensity hadron beams from RHIC with a 50-mA electron beam from a six-pass 30GeV Energy Recovery Linac (ERL), which will utilize 704 MHz superconducting RF accelerating structures. This paper describes the eRHIC SRF linac requirements, layout and parameters, five-cell SRF cavity with a new HOM damping scheme, project status, and plans.

2014

The article presents a new design of a CW RF high average current superconducting injector cavity. This design allows recovering energy in the injector, improving beam parameters and energy efficiency, reducing injector size, cost and avoiding high average power coupler problem.

2015

A 650 MHz SRF deflecting mode cavity has been designed for the ARIEL e-Linac to separate interleaved beams heading towards either Rare Ion Beam production or a recirculation loop for energy recovery, allowing the e-Linac to provide beam delivery to multiple users simultaneously. The cavity geometry has been optimized for the ARIEL specifications, resulting in a very compact cavity with high shunt impedance and low dissipated power. Analyses have been performed on the susceptibility to multipacting, input coupling considering beam loading and microphonics, and extensive studies into the damping of transverse and longitudinal higher order modes. The pressure sensitivity, frequency tuning, and thermal behaviour have also been studied using ANSYS. The cavity design resulting from these considerations will be discussed here.

Proceedings of the 1997 Particle Accelerator Conference (Cat. No.97CH36167), 1998

Two superconducting radiofrequency quadrupoles, SRFQ1 and SRFQ2, resonating at 80 MHz, will provide acceleration from b=v/c=0.009 to 0.035 in PIAVE, the new injector for the superconducting linac ALPI at INFN -Laboratori Nazionali di Legnaro . The construction of the full niobium structures was preceded by the development of a full size stainless steel prototype of SRFQ2 ( , through which most of the construction techniques also applying to the niobium cavities, electromagnetic characterization of the resonator and its mechanical vibration spectrum can be investigated. This paper presents the most relevant design issues of the superconducting RFQ resonators and the construction techniques adopted.

2011

As a first step towards a high brightness, high average current electron source for the BERLinPro ERL a fully superconducting photo-injector was developed by HZB in collaboration with Jefferson Laboratory, DESY and the A. Soltan Institute. This cavity-injector ensemble is made up of a 1.6-cell superconducting cavity with a superconducting lead cathode deposited on the half-cell backwall. A superconducting solenoid is used for emittance compensation. This system, including a diagnostics beamline, has been installed in the HoBiCaT facility to serve as a testbed for beam dynamics studies and to test the combination SRF cavity and superconducting solenoid. This paper summarizes the characterization of the cavity in this configuration including Q measurements, dark current tests and fieldstability analyzes.

The injector for the UK's New Light Source project is required to deliver low emittance 200 pC electron bunches at a repetition rate of up to 1 MHz. Initial design of a photoinjector based around a 1½ cell L-band superconducting RF gun able to meet these requirements is presented, including beam dynamic simulations of the injector up to the end of the first linac module.

The ISAC-II superconducting linac is presently being commissioned. Twenty cavities have been prepared and characterized in single cavity tests before mounting in the on-line cryomodules. The cavities are specified to operate at a challenging peak surface field of 30 MV/m to supply an accelerating voltage of 1.1 MV/cavity. An overview of the rf systems will be given. We will describe the early operat-ing experience and compare the cavity on-line performance with the single cavity characterizations.