Novel Ultra-High Power Microwave Isolators

Microwave isolators are highly desired for high-power RF (radio-frequency) systems that drive linear accelerators. Reflected power from the accelerator can destabilize the RF system and reduce the life of the RF source requiring expensive replacement. The available isolators are costly and have limited reliability and power-handling capabilities. High power isolators are also of interest to DOE laboratories with high energy accelerators and in these systems the power is so high, there is no viable device that can be used. The company proposes a new class of isolators scalable, in principle, to extremely high-power levels. These novel devices are compact and promise low cost in production. These devices are based on a recent invention of a new microwave device called the “polarizer”. The topology of the polarizer allows for the synthesis of a scalable modular structure for arbitrary power levels. This project will design and manufacture prototypes of the isolators at the three frequencies most commonly used in industry and national laboratories. The isolators will be tested at high-power facilities at national labs, universities and industry. A test isolator microwave structure at X-band was designed and constructed with the ability to use different garnet materials. It was placed inside an electromagnet to characterize the garnet materials. The device properties were tested and the results were compared to the theoretical prediction and simulations. In the actual isolator the appropriate magnetic field will be provide using permanent magnet material and a design for this magnet has been made. A compact, dry, high-power RF load was designed to be integrated with the isolator. In Year 1, prototypes of isolators and associated RF loads at different frequencies will be built and tested with high power RF. In Year 2, lessons learned from these prototypes will be used to design, build and commission production versions of isolators/loads at S-band, X-band and Ku-band.Commercial Applications and Other Benefits All medical linacs and linac-based security systems use RF isolators and the market is large, e.g. Varian alone manufactures 500 such systems a year. The proposed isolator will be more reliable, capable of handling much higher powers and more cost-effective. Reducing the overall manufacturing and operational costs of linacs for medical, industrial and security applications and improving their reliability is key to more widespread applications of such systems. Isolators capable of 10’s of MW power handling capability which can be used in HEP accelerators can be similarly designed.