Fermilab, Batavia
DESY, Hamburg
A 4-cavity 3.9 GHz cryomodule has been constructed at Fermilab and delivered to DESY. Its intended use is to linearize the non-linear beam energy-time profile produced by the 1.3 GHz accelerating gradient and thus improve the operating characteristics of FLASH for its users. First cold testing of the module is expected in the near future prior to its installation. We will report on the performance of the cavities, assembly and transport of the module as well as anticipated testing, installation, and commissioning plans.
Fermilab, Batavia
Five 3.9 GHz 9 cell cavities have been measured for the DESY FLASH module. These cavities were BCP processed and reached gradients of typically about 25 MV/m with Q drop starting at about 20 MV/m. Recently one cell cavities have been processed with EP and at least one has tested to a gradient of 30 MV/m with Q drop starting at about 25 MV/m. We will compare the results and give an update to the thermal analysis in relation to global thermal breakdown at 3.9 GHz.
Fermilab, Batavia
The Fermilab High Intensity Neutrino Source (HINS) linac R&D program is building a pulsed 30 MeV superconducting H- linac. The linac incorporates superconducting solenoids, high power RF vector modulators and superconducting spoke-type accelerating cavities starting at 10 MeV. This will be the first application and demonstration of any of these technologies in a low-energy, high-intensity proton/H- linac. The HINS effort is relevant to a high intensity, superconducting H- linac that might serve the next generation of neutrino physics and muon storage ring/collider experiments. In this paper we present the RF design, the mechanical design, the fabrication, the chemistry and testing of the first two SSR1 (Single Spoke Resonator type 1) prototype cavities. These cavities operate at 325 MHz with β=0.21. The design and testing of the input coupler and the tuning mechanism are also discussed.
Fermilab, Batavia
Alternative option of Project X is based on the CW SC 2GeV Linac with the average current 1mA. Possible option of the CW Linac considered in the paper includes low energy part consisted of a few families SC Spoke cavities (from 2.5 MeV to 466 MeV) and high energy part consisted of 2 types of elliptical cavities (v/c=0.81 and v/c=1). Requirements and designed parameters of cavities are considered.
Fermilab, Batavia
Fermilab has developed a TIG welding procedure that will attach a 9-cell 1.3GHz niobium cavity to a titanium helium vessel. These welds were designed to meet ASME Boiler & Pressure Vessel Codes, Division 1 and are full penetration welds. The cavities produced will be used in Japan’s S-1 Global cryomodule, Fermilab’s Project X cryomodules, International Linear Collider and the current Type IV Cryomodules (T4CM). Discussed in further detail will include: Setting up electron beam weld parameters for Ti transition rings for the cavities. On-going work with U.S. vendors to produce reliable helium vessels that pass mechanical inspections, vacuum requirements and X-rays. Tooling requirements for the assembly and alignment of the cavity to the helium vessel. Settings that are applied to the Glovebox environment to produce the best quality TIG welds. What test measurements are taken throughout the process to monitor the cavity for excessive cell deformation due to the heat loads from the welding, and results from HTS on the fist dressed cavity.
Fermilab, Batavia
Fermilab is developing 325 MHz SRF spoke cavities for the proposed High Intensity Neutrino Source. A compact fast/slow tuner has been developed to control Lorentz force detuning and compensate for liquid He pressure fluctuations. The design of a fast/slow tuner and a summary of results from warm tests of the tuner will be presented.
DESY, Hamburg
Fermilab, Batavia
A semi-automatic cavity tuning machine is used at DESY since 15 years to tune the field flatness and concentricity of the TESLA shape 9 cell cavities for FLASH. Based on this experience a further development work was done in a collaboration effort among FNAL, DESY and KEK to support the high throughput cavity fabrication necessary for the European XFEL and other SRF based future projects. Two of the four machines will be delivered to and operated by the cavity vendors for the tuning of the XFEL cavities. We describe the mechanical design and functionality of these machines and discuss the safety aspects for the operation at the industry.
Fermilab, Batavia
BNG, Würzburg
Fermi National Accelerator Lab is continuing to improve its infrastructure for research and development on the processing of superconducting radio frequency cavities. A single cell 3.9 GHz electropolishing tool built at Fermilab and operated at an industrial partner was recently commissioned. The EP tool was used to produce a single cell 3.9 GHz cavity that reached an accelerating gradient of 30 MV/m with a quality factor of 5 109. A single cell 1.3 GHz cavity was also electropolished at the same industrial vendor using the vendor’s vertical full-immersion technique. On their first and only attempt the vendor produced a single cell 1.3 GHz cavity that reached 30 MV/m with a quality factor of 1 1010. These results will be detailed along with preliminary tumbling results.