All posts by Lawrence Ives

New, High Efficiency, RF System for Superconducting Accelerators

CCR completed assembly of a new, high efficiency RF source for driving superconducting accelerator cavities. The system uses a high efficiency magnetron that is phase locked for precise frequency and phase control. Amplitude control is achieved in real-time by phase modulating the locking signal. This allows feedback control of the magnetron phase and output power. The prototype system is designed to produce 100 kW at 1.3 GHz.  System testing is scheduled for spring 2017.

Magnetron Test System Under Construction

CCR is making good progress inSystem Model 1 assembling a 100 kW RF magnetron RF source system with phase and amplitude control. This will provide  lower cost  RF power than currently available from klystrons, with a significant increase in efficiency.  The system uses a phase modulated locking signal to provide amplitude control when driving high Q accelerator cavities.  The initial test will determine the magnitude of the RF signal required to lock the magnetron. This will provide information to replace the existing klystron driver with a solid state driver.

The system consists of the magnetron, circulator, RF driver, coolant system, PLC-based interlock system, driver power supply, and diagnostic instrumentation. It is anticipated the system will be completed near the end of July with high power testing scheduled for mid-August.  Following tests at CCR, the system will be tested with a superconducting cavity at Fermi National Laboratory . CCR intends to market this system as an economical source of RF power for superconducting accelerators.

Brewster Window Under Test at General Atomics

CCR’s 1.5 MW CW Brewster Window is currently being tested at General Atomics using a gyrotron at the DIII-D tokamak facility. The window is installed in transmission line between the Mirror Optical Unit (MOU) and high power load. The tests are characterizing the performance, including reflection and potential mode conversion and will eventually transmit the highest RF power level available from the gyrotron. Cameras will  look for arcing and power deposition in the CVD diamond window. Testing will Labeled Window Installationcontinue for the next couple of months, depending on availability of the gyrotron and associated power supplies. Test results will be presented at the IR & MM-Wave Conference in Copenhagen in September.

CCR Receives Navy Contract to Develop Corrosion Mitigation Technology

The U.S. Navy awarded CCR a $1M contract to develop technology to reduce corrosion in RF sources and solenoids. This addresses issues caused by sub-standard coolant water on ships in the fleet. CCR will team with North Carolina State University to develop Atomic Layer Deposition processes and equipment to deposit a protective coating inside copper-based cooling circuits.  This equipment would be installed at OEMs manufacturing traveling wave tubes, klystrons, magnetrons, and associated equipment.  The goal is to triple the lifetime of these devices, which would result in significant cost savings for the Navy. It is anticipated this technology would be applicable to any water cooled device installed where high quality cooling water is not easily available,  including remote locations and developing countries.ALD Schematic

5.5 MW PPM-Focused Klystron Ready for Testing

Tube for testing

CCR completed the assembly of a PPM-focused klystron designed to generate 5.5 MW of RF power at S-Band. The klystron is targeted for the next generation of cancer therapy devices. The elimination of the solenoid will reduce the size of the RF source system, allowing a smaller cancer-treatment device.

The klystron magnetic circuit uses an innovative design that provides an azimuthally symmetric field while providing access to the cavities for tuners and water cooling. This prototype tube includes tuners on five cavities. After determination of the optimum cavity frequencies, the tuners will  be removed to reduce the production cost.

This program is funded by the U.S. Department of Energy through grant number DE-SC0007591.

Diamond Brewster Window Cold Testing

CCR_BrewsterWindow_diamond4CCR completed the assembly of its 1.5 MW CW, diamond Brewster angle window and shipped it to MIT for lower power testing. MIT will test the window using their unique facilities to generate the HE11 mode in corrugated waveguide. Once the tests at MIT are complete, the window will be shipped to General Atomics for high power testing in the DIII-D transmission line.

C-Band Multiple Beam Klystron Shipped

Calabazas Creek Research, Inc. shipped a 125 kW, C-Band klystron with 18 beams. This is the culmination of an 18-month development program to build a wide-band, low voltage klystron. The tube operates at 25 kV with a bandwidth exceeding 6%. It uses controlled porosity reservoir cathodes and includes an extended interaction output cavity. The klystron is currently being installed for high power testing at the customer’s site. C-Band MBK

Load Reflector Assembly Completes Testing

Life testing of the reflector assembly for CCR’s 1.5 MW CW RF load assembly was terminated on January 3rd after operating for more than 410,000 cycles. The assembly was still operating satisfactorily when the testing was stopped. This is more than twice the expected lifetime for a load in operation at a gyrotron facility. The assembly is being disassembled to determine areas where the design can be improved. These improvements will be implemented to further improve the reliability of the device. The previous post provides a video of the assembly operating in the testing structure.

1.5 MW RF Load Reflector Testing

Testing has begun on the RF reflector drive system for CCR’s new, 1.5 MW CW, RF load for gyrotrons. The new design eliminates rotating seals and bearings. The reflector is mounted to a hollow shaft passing through a stainless steel bellows that supports the reflector and provides water cooling. An external motor swings the reflector around the waveguide launcher that delivers RF power to the load. The reflector sweeps the RF power around the load interior, preventing excessive power densities and standing modes inside the structure.
The new design meets specifications for ITER, the international fusion reactor now under construction in France. Approximately 24 loads will be required for the initial phase.
The video below shows life testing of the the reflector support assembly. A dummy cone on the shaft duplicates the weight of the copper, water-cooled cone that will be used in the actual load.

PPM-Focused Klystron completes bakeout

CLINAC following bakeout

CCR’s Periodic Permanent Magnet (PPM) focused klystron completed bakeout today. The tube is currently being prepared for high power testing at Communications & Power Industries, LLC. The klystron is being developed for a new generation of cancer therapy machines (CLINACs) produced by Varian Medical Systems, Inc.  The PPM-focused klystron would replace traditional solenoid-focused klystrons, reducing the size and weight of the system.

The klystron is designed to produce 5.5 MW RF pulses at 2.856 GHz at approximately 50% efficiency.  This development is funded by the U.S. Department of Energy through grant number DE-SC0007591.