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.
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.
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.
During the past several months, we’ve been extensively testing BOA beta version 6.3 and it is now ready for primetime. It uses the latest Simmetrix solid model and meshing libraries and the most recent DisLin plotting library for portability and implementation of UI interfaces. New features are listed below. More detailed information is available in the Release Notes at http://calcreek.com/products/software/.
New features in BOA v6.3 include:
• Option to use Inverse Cumulative Density Function technique for thermal effects in thermionic emission,
• More intuitive and simplified menu for beam optics display pane, especially for model background and symmetries,
• Models with built-in symmetries can now be specified.
• Both global and project level persistent preferences can be set via File, Options and View, User View Preferences, respectively,
• Parallel IO particle data are now available,
• Ability to plot images of power density from a 3D surface in either color or gray scale. Display power density on 3D surfaces in either color or gray scale,
• Plot emittances or brightnesses along a global or arbitrary axis.
• Injection of particles with arbitrary coordinates without specifying an injection plane in model. This is convenient for multipactoring ePIC simulations.
CCR is nearing completion of its photocathode fabrication chamber. The main chamber was assembled and baked in March. The vacuum suitcase was assembled and is currently being baked. Figure 1 shows a photo of the chamber with the suitcase attached.
During the next couple of weeks we’ll be installing the support for the sputtering source and the internal support for the photocathode being processed. We also need to mount the laser and connect the picoammeter. We had a small setback when problems arose with our turbo pump. That’s now been replaced, and we’re moving forward again.
We’ll first fabricate cesium antimonide photocathodes. The antimony source will be installed in the next couple of weeks. We still need to assemble the first test photocathode with parts in stock. I’m hoping we can fabricate our first cathode by the end of November.
This program is funded by U.S. Department of Energy Grant No. DE-SC00009583.
R. Lawrence Ives, Ph.D.
Dr. Ives received his Ph.D. from N.C. State University in plasma physics and began his microwave career in the Gyrotron Department at Varian Associates, Inc. in Palo Alto, CA. In that position he was responsible for designing electron guns, gyrotron circuits, collectors, and waveguide components. Gyrotrons are high power, high frequency microwave and millimeter wave RF sources used for fusion research and industrial heating.
Dr. Ives founded Calabazas Creek Research, Inc., which is involved in software development, microwave tube and component design, and uses of microwave power for environmental and heating applications.
Dr. Ives was principle investigator in programs to develop a two-stage depressed collector system for Gaussian-mode gyrotrons at the 2 MW CW power level, S-Band multiple beam electron gun for radar applications, a MW CW waterload for Gaussian mode gyrotrons, and a 15 kW CW L-Band klystron for Driving Superconductor Accelerator Cavities.
Dr. Ives is currently principle investigator on the following programs to implement field emission array cathodes into RF sources, multiple beam electron guns for high power RF applications, improved magnetron injection guns for high power gyrotrons and gyroklystrons, a 50 MW multiple beam klystron, a microfabricated W-Band Traveling Wave Tube for satellite communications, and Terahertz backward wave oscillators.
Dr. Ives also provides consulting support to several commercial companies on electron gun and RF source development.
Prior to founding CCR, Dr. Ives was manager of Varian's High Power Klystron department, responsible for overseeing klystron design and development from S-Band through X-Band. He was responsible for managing and upgrading the computational facility, which supported four divisions and was recognized as the most powerful and advanced in the microwave industry. He was responsible for implementing Computer Integrated Manufacturing (CIM) techniques, including interfacing CNC machines to the engineering system. Dr. Ives returned to a more technical role as Senior Engineer, supporting research in both the klystron and gyrotron areas. In that position he managed development programs for high power CW klystron amplifiers; high voltage, high current electron guns for research purposes; and ultrahigh power window designs for klystrons. Dr. Ives developed the first commercial gyrotron capable of operation with a depressed collector. He also designed the output window and waveguide system for an experimental, 200 MW, X- Band klystron using advanced scattering matrix and mode matching computer techniques.