Ultra-Efficient X-Band Solid State Power Amplifier for RF Accelerators

RF accelerator applications currently rely on large, costly, and archaic traveling wave tubes (TWT), which are also very inefficient and offer lower power compared to the solid state power amplifier (SSPA) proposed under this Phase-2 project. These factors limit the possibilities of new applications – such as compact linear accelerators for beam manipulation – and are a key reason national laboratories such as SLAC have endorsed the development of this SSPA and why agencies such as the DOE are seeking solid state products “as a TWT replacement for driving short-pulse klystrons” and in other similar end applications – per the 2024 DOE Funding Opportunity Announcement. The company will develop this amplifier by utilizing high-power Gallium Nitride semiconductor technology, and by starting at the design of the essential unit-cell SSPA all the way through to an optimized custom-developed power combiner which will achieve a power added efficiency of over 70% and a peak output power exceeding 5 kW at a frequency of 11.424 GHz. These specifications and narrow bandwidth are customer-driven, and have been determined after substantive conversations with persons from the DOE, various national laboratories, and prospective customers in the commercial and defense spaces. : Phase-1 focused on developing a unit-SSPA/pallet-SSPA module. The preliminary Unit-SSPA/Pallet-SSPA design developed during Phase-1 showcased an ~800W gallium-nitride (GaN) based amplifier module as the foundational building block for an ultra-efficient 5-kW X-Band SSPA system. Phase- 1 demonstrated feasibility through design simulations and circuit layout, which indicate that the unit-SSPA achieves 72% power-added efficiency (PAE) with an output of over 900 W. During Phase-2, the company will refine the SSPA architecture, designing and fabricating GaN transistor RF power-bars and driver amplifiers, and performing high-power transistor modeling to support SSPA design, with a significant portion of the effort dedicated to developing the Unit-SSPA/Pallet-SSPA module. As attested to in the letters of commitment provided in Appendix A of the Commercialization Plan, the SSPA has immediate and validated drop-in value for a multitude of both current and future RF accelerator applications and experiments, for example, in compact linacs and beam manipulation experiments such as X-band deflecting cavities for injector beam diagnostics. Development of this product and technology will also bolster national research which hinges on RF accelerators, and directly aligns with the U.S.’s strategic goal of reinforcing leadership within the semiconductor industry – a commitment directly reflected in legislative measures such as the CHIPS Act. By offering a product with far superior performance and at drastically reduced cost structures, the company has a clear path to immediate commercialization.