Christiana Grenoble

RF Conditioning and Testing of Fundamental Power Couplers for SNS Superconducting Cavity Production

The Spallation Neutron Source (SNS) makes use of 33 medium beta (0.61) and 48 high beta (0.81) superconducting cavities. Each cavity is equipped with a fundamental power coupler, which should withstand the full klystron power of 550 kW in full reflection for the duration of an RF pulse of 1.3 msec at 60 Hz repetition rate. Before assembly to a superconducting cavity, the vacuum components of the coupler are submitted to acceptance procedures consisting of preliminary quality assessments, cleaning and clean room assembly, vacuum leak checks and baking under vacuum, followed by conditioning and RF high power testing. Similar acceptance procedures (except clean room assembly and baking) were applied for the airside components of the coupler. All 81 fundamental power couplers for SNS superconducting cavity production have been RF power tested at JLAB Newport News and, beginning in April 2004 at SNS Oak Ridge. This paper gives details of coupler processing and RF high power-assessed performances.

SNS cryomodule performance

Thomas Jefferson National Accelerating Facility, Jefferson Lab, is producing 24 Superconducting Radio Frequency (SRF) cryomodules for the Spallation Neutron Source (SNS) cold linac. This includes one medium-/spl beta/ (0.61) prototype, 11 medium-/spl beta/ production, and 12 high beta (0.81) production cryomodules. After testing, the medium-/spl beta/ prototype cryomodule was shipped to Oak Ridge National Laboratory (ORNL) and acceptance check out has been completed. All production orders for cavities and cryomodule components are being received at this time and the medium-/spl beta/ cryomodule production run has started. Each of the medium-/spl beta/ cryomodules is scheduled to undergo complete operational performance testing at Jefferson Laboratory before shipment to ORNL. The performance results of cryomodules to date will be discussed.

Overview of SNS Cryomodule Performance

Thomas Jefferson National Accelerating Facility (Jefferson Lab) has completed production of 24 Superconducting Radio Frequency (SRF) cryomodules for the Spallation Neutron Source (SNS) superconducting linac. This includes one medium-β (0.61) prototype, eleven medium-β and twelve high-β (0.81) production cryomodules. Nine medium-β cryomodules as well as two high-β cryomodules have undergone complete operational performance testing in the Cryomodule Test Facility at Jefferson Lab. The set of tests includes measurements of maximum gradient, unloaded Q (Q0), microphonics, and response to Lorentz forces. The Qext’s of the various couplers are measured and the behavior of the higher order mode couplers is examined. The mechanical and piezo tuners are also characterized. The results of these performance tests will be discussed in this paper.

RF and data acquisition systems for fermilab's ILC SRF cavity vertical test stand

Fermilab is developing a facility for vertical testing of SRF cavities as part of its ILC program. The RF system for this facility is based on the proven production cavity test systems used at Jefferson Lab for CEBAF and SNS cavity testing. The design approach is modular in nature, using commercial-off-the-shelf (COTS) components. This yields a system that can be easily debugged and modified, and with ready availability of spares. Comprehensive data acquisition and control is provided by a PXI-based hardware platform in conjunction with software developed in the Lab View programming environment.