MIT successfully tested CCR’s internal converter for gyrotrons. The coupler converted 1.12 MW of RF power into an HE11 mode in corrugated waveguide inside the vacuum envelope of the gyrotron. This could potentially reduce the cost of gyrotrons by more than $100K and eliminate requirements for Mirror Optical Units, which reduces the cost of electron cyclotron heating systems approximately $500K per gyrotron. CCR presented these results at the RF Heating Technology Workshop in Santa Monica on September 7th. The MIT test performance is compared with the conventional multi-mirror Gaussian output converter in the accompanying figure.
The U.S. Department of Energy awarded CCR two new programs to advance RF source technology. CCR will work with SLAC National Accelerator Laboratory to develop high efficiency klystrons for the next generation of accelerators. The goal is to provide klystrons operating at efficiencies exceeding 85%, which is considerably higher than current technology. In the second program, the company will team with N.C. State University to explore additive manufacturing of klystrons. If successful, this will dramatically reduce the price of RF sources for accelerators, particularly for big science programs where hundreds or thousands of a single klystron type will be required. The program will address issues with additive manufacturing of copper, ensuring material quality, and providing the required finish for high field surfaces. The test device will be a klystron used in commercial cancer therapy accelerators.
Calabazas Creek Research is nearing completion of an Atomic Layer Deposition system to mitigate corrosion in copper cooling channel in RF sources and similar devices. The system applies a thin ceramic coating over all internal surfaces to separate the metal structure from the coolant fluid, effectively eliminating corrosion. The technology has been extensively tested, including accelerated life testing.
The photograph shows the prototype system nearing completion. First operation is scheduled for the end of August with installation into a traveling wave tube factory in September. This development is funded by the U.S. Navy.
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.
CCR is making good progress in 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.
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 continue 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.
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.
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.
CCR 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.
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.