[en] Following successful testing of a concept prototype of a waveguide-based high power phase shifter, a design of a fast, high power device has been developed. The shifter uses two magnetically biased blocks of Yttrium Iron Garnet (YIG) positioned along the side walls of a rectangular waveguide. The cross-section of the waveguide is chosen to suppress unwanted RF modes that could otherwise compromise performance of the phase shifter. Static bias field in the YIG blocks is created by employing permanent magnets. Low inductance coils in the same magnetic circuit excite fast component of the bias field. Design of the device ensures effective heat extraction from the YIG blocks and penetration of the fast magnetic field inside the waveguide with minimum delay. This paper summarizes main steps in this development and gives brief description of the system

[en] Superconducting cavities with high operating Q will be installed in the Project-X, a superconducting linac, which is under development at Fermilab. Possibility of cavity design without HOM couplers considered. Rich spectrum of the beam and large number of cavities in ProjectX linac can result to resonance excitation of some high order modes with high shunt impedance. Under scope of study of High order modes damping the manipulation with HOM spectrum in cold linac is considered. Results of detuning HOM spectrum of 1.3 GHz cavities at 2K in Horizontal Test Station of Fermilab are presented. Possible explanation of the phenomena is discussed.

[en] The proposed High Intensity Neutrino Source (HINS) at Fermilab is based on an 8 GeV linear proton accelerator that consists of a normal-conducting (warm) and a superconducting section. The warm section is composed of an ion source, a radio frequency quadrupole, a medium energy beam transport (MEBT) and 16 warm Crossbar H-type (CH) cavities that accelerate the beam from 2.5 MeV to 10 MeV (from β=0.0744 to β=0.1422). These warm cavities are separated by superconducting solenoids enclosed in individual cryostats. Beyond 10 MeV, the design uses superconducting spoke resonators to accelerate the beam up to 8 GeV. In this paper, we illustrate the completion of the first warm CH cavity (β=0.0744) explaining in detail the mechanical engineering aspects related to the machining and brazing processes. The radio-frequency (RF) measurements and tuning performed at Fermilab on the resonator and comparisons with simulations are also discussed

[en] Front end of a CW linac of the Project X contains an H^- source, an RFQ, a medium energy transport line with the beam chopper, and a SC low-beta linac that accelerates H^- from 2.5 MeV to 160 MeV. SC Single Spoke Resonators (SSR) will be used in the linac, because Fermilab already successfully developed and tested a SSR for beta = 0.21. Two manufactured cavities achieve 2.5 times more than design accelerating gradients. One of these cavities completely dressed, e.g. welded to helium vessel with integrated slow and fast tuners, and tested in CW regime. Successful tests of beta = 0.21 SSR give us a confidence to use this type of cavity for low beta (0.117) and for high-beta (0.4) as well. Both types of these cavities are under development. In present report the basic constrains, parameters, electromagnetic and mechanical design for all the three SSR cavities, and first test results of beta = 0.21 SSR are presented.

[en] A novel prototype of SCRF cavity tuner is being designed and tested at Fermilab. This is a superconducting C-type iron dominated magnet having a 10 mm gap, axial symmetry, and a 1 Tesla field. Inside the gap is mounted a superconducting coil capable of moving ± 1 mm and producing a longitudinal force up to ± 1.5 kN. The static force applied to the RF cavity flanges provides a long-term cavity geometry tuning to a nominal frequency. The same coil powered by fast AC current pulse delivers mechanical perturbation for fast cavity tuning. This fast mechanical perturbation could be used to compensate a dynamic RF cavity detuning caused by cavity Lorentz forces and microphonics. A special configuration of magnet system was designed and tested

[en] 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.

[en] After about 40 years of operation the RF accelerating cavities in Fermilab Booster need an upgrade to improve their reliability and to increase the repetition rate in order to support a future experimental program. An increase in the repetition rate from 7 to 15 Hz entails increasing the power dissipation in the RF cavities, their ferrite loaded tuners, and HOM dampers. The increased duty factor requires careful modelling for the RF heating effects in the cavity. A multi-physic analysis investigating both the RF and thermal properties of Booster cavity under various operating conditions is presented in this paper.

[en] Fermilab is developing 325 MHz SRF spoke cavities for the proposed Project X. A compact fast/slow tuner has been developed for final tuning of the resonance frequency of the cavity after cooling down to operating temperature and to compensate microphonics and Lorentz force detuning (2). The modified tuner design and results of 4.5K tests of the first prototype are presented. The performance of lever tuners for the SSR1 spoke resonator prototype has been measured during recent CW and pulsed tests in the Fermilab SCTF. The tuner met or exceeded all design goals and has been used to successfully: (1) Bring the cold cavity to the operating frequency; (2) Compensate for dynamic Lorentz force detuning; and (3) Compensate for frequency detuning of the cavity due to changes in the He bath pressure.

[en] One of the approaches to power distribution system of a superconducting proton linac under discussion at FNAL requires development of a fast-action, megawatt-range phase shifter. Using a couple of this kind of devices with a waveguide hybrid junction can allow independent control of phase and amplitude of RF power at the input of each superconducting cavity, which will result in significant saving in number of klystrons and modulators required for the accelerator. A prototype of a waveguide version of the shifter that uses Yttrium-Iron Garnet (YIG) blocks was developed and tested. This report presents design concept of the device, and main results of simulation and proof-of-principle tests

[en] A new superconducting RF cavity test facility has been commissioned at Fermilab in conjunction with first tests of a 325 MHz, β = 0.22 superconducting single-spoke cavity dressed with a helium jacket and prototype tuner. The facility is described and results of full gradient, CW cavity tests with a high Q_ext drive coupler are reported. Sensitivities to Q disease and externally applied magnetic fields were investigated. Results are compared to bare cavity results obtained prior to hydrogen degassing and welding into the helium jacket.