LANL, Los Alamos, New Mexico, USA
At the Los Alamos Neutron Science Center (LANSCE), we are considering various topologies to replace obsolete charging supplies and capacitor banks that provide high-voltage direct-current (DC) power to the 44, 805-MHz klystron modulators that drive the LANSCE Coupled Cavity Linac (CCL). Among the possible replacement topologies is the High Voltage Converter Modulator (HVCM), originally designed at LANSCE for use at the Spallation Neutron Source (SNS), to be used as a pulsed high-voltage power supply for klystron-based RF transmitters. The HVCM topology uses high frequency transformers with resonant LC networks for efficient energy conversion and a frequency dependent gain, which permits the use of frequency modulation as a control variable to afford pulse flattening and excellent regulation as demonstrated at SNS. A mathematical analysis is presented that links the converter resonant tank components to the frequency dependent output behavior of the converter modulator.
LA-UR-22-25179
LANL, Los Alamos, New Mexico, USA
This presentation will report initial results of high gradient testing of two C-band accelerating cavities fabricated at Los Alamos National Laboratory (LANL). At LANL, we commissioned a C-band Engineering Research Facility of New Mexico (CERF-NM) which has unique capability of conditioning and testing accelerating cavities for operation at surface electric fields at the excess of 300 MV/m, powered by a 50 MW, 5.712 GHz Canon klystron. Recently, we fabricated and tested two benchmark copper cavities at CERF-NM. These cavities establish a benchmark for high gradient performance at C-band and the same geometry will be used to provide direct comparison between high gradient performance of cavities fabricated of different alloys and by different fabrication methods. The cavities consist of three cells with one high gradient central cell and two coupling cells on the sides. The ratio of the radius of the coupling iris to the wavelength is a/λ=0.105. This poster will report high gradient test results such as breakdown rates as function of peak surface electric and magnetic fields and pulse heating.
ORNL, Oak Ridge, Tennessee, USA
JLab, Newport News, Virginia, USA
ORNL RAD, Oak Ridge, Tennessee, USA
Arizona State University, Tempe, USA
The Compact X-ray Light Source (CXLS) uses inverse Compton scattering of a high intensity laser off a bright, relativistic electron beam to produce hard x-rays. The accelerator consists of a photoinjector and three standing-wave linac sections, which are powered by two 6-MW klystrons operating at 9.3 GHz with a repetition rate of 1 kHz. This paper presents the design and commissioning of the CXLS RF systems consisting of both high-power RF structures and low-power diagnostics. The high-power RF system is comprised of two solid state amplifier and klystron modulator sets, various directional couplers, and three phase shifter power dividers. The low-level system consists of a master oscillator and laser phase lock, IQ modulators, IQ demodulators, and downconverters. We present measurements of the low-level and high-power RF phase and amplitude stability showing RMS timing jitter in the tens of femtoseconds and amplitude jitter below 0.1% at high power.
Arizona State University, Tempe, USA
To protect against fault conditions in the high-power RF transport and accelerating structures of the Arizona State University (ASU) Compact X-Ray Light Source (CXLS), the Machine Protection System (MPS) extinguishes the 6.5-MW RF energy sources within approximately 50 ns of the fault event. In addition, each fault is localized and reported remotely via USB for operational and maintenance purposes. This paper outlines the requirements, design, and performance of the MPS applied on the CXLS.
BNL, Upton, New York, USA
The Multi-Bunch Mode (MBM) beam injection opera-tion of NSLS-II LINAC requires a beam-loading compen-sation for its rf field. That requirement has a significant impact on its radio frequency system (RF), in both the low-level rf control and the high-power klystron transmit-ters. Specifically, for the rf control, it requires the output vector modulation have enough bandwidth to be able to respond the transients by the MBM beam of 40~300 nS long. For the high-power rf transmitters, it requires the klystrons to operate in a near-linear region to be able to respond the linear rf control for the beam-loading compensation, which means a need of ~30% extra rf power overhead, compared to the single-bunch mode operations. The digital signal processing and the network configuration for the rf controllers are also the important areas in the implementation. The original system design was driven by the MBM beam operation requirements, and our system upgrade today continues to be guided by the same principles.
LANL, Los Alamos, New Mexico, USA
We will report on the status of two C-band test facilities at Los Alamos National Laboratory (LANL): C-band Engineering Research Facility in New Mexico (CERF-NM), and Cathodes and Rf Interactions in Extremes (CARIE). Modern applications such as X-ray sources require accelerators with optimized cost of construction and operation, naturally calling for high-gradient acceleration. At LANL we commissioned a high gradient test stand powered by a 50 MW, 5.712 GHz Canon klystron. CERF-NM is the first high gradient C-band test facility in the United States. It was fully commissioned in 2021. In the last year, multiple C-band high gradient cavities and components were tested at CERF-NM. Currently we work to implement several updates to the test stand including the ability to remotedly operate at high gradient for the round-the-clock high gradient conditioning. Adding capability to operate at cryogenic temperatures is considered. The construction of CARIE will begin in October of 2022. CARIE will house a cryo-cooled copper RF photoinjector with a high quantum-efficiency cathode and a high gradient accelerator section.
