#insights

The current trend in radio frequency (RF) power systems in many large scientific facilities is to use solid-state power amplifiers (SSPA). When feasible, replacing vacuum technology with solid-state technology brings advantages, which is why the latter has been selected for the RF power system at IFMIF-DONES (International Fusion Materials Irradiation Facility).

However, reaching the high power levels of vacuum technology with SSPA requires combining many solid-state devices. Hence, the search for efficient techniques for combining RF power is essential to the development of SSPA.

The 160-input resonant cavity combiner developed by Sener is the result of applying an innovative cavity combination technique that achieves high power and efficiency in a single step. This helps minimize the general losses of traditional combination and reduces the size compared to the usual combination schemes.

The research work at Sener Aeroespacial has yielded and validated a CW, 160-input, water-cooled cavity combiner at 175 MHz and up to 100 kW. This work presents an alternative strategy to validate the high-power experiments that reduces the number of high-power components needed for the experiment and simplifies the test bench.

During the campaign, Sener Aeroespacial team confirmed that the effectiveness of the combination exceeds 99%, both in small-signal and high-power tests. They similarly demonstrated that the resonant cavity combination provides a highly efficient combination of multiple signals in a single step. As a result, they have proposed developing a future 200-kW SS RF station prototype for the IFMIF-DONES RF system, instead of using a traditional corporate combination.

The next step is to validate the CW cavity combiner at 200 kW, the highest power required by the IFMIF-DONES accelerator cavities, to definitively demonstrate its feasibility for the RF power system of IFMIF-DONES.

Thanks to this work, Sener Aeroespacial is a world leader in the technological development of components for the aerospace industry.

A recently published paper in the prestigious industry journal “Fusion Engineering and Design” presents the first results of the operation of the 160-coaxial input combiner based on cavity technology for high RF powers, which demonstrates the success of the research work carried out at Sener Aeroespacial.

The design and manufacture of this combiner is part of a program called ACTECA, Accelerators and Technologies for Large Scientific Facilities, financed by the Center for Industrial Technological Development (CDTI) and promoted by the state-owned Center for Energy, Environmental and Technology Research (CIEMAT). Both belong to the Ministry of Science and Innovation.

The creation of this 160-input combiner offers a solution to the problem of achieving power that is also able to withstand the harsh conditions inside future fusion reactors, and confirms IFMIF_DONES as one of the leading facilities in Europe for generating electricity from fusion. In the article “High power experiments of the prototype solid state RF System for IFMIF-DONES”, Sener Aerospace engineers Sasa Dragas and Antonio José Martínez, in collaboration with scientists from CIEMAT and BTESA, detail the results of the first operating tests of the 160-input resonant cavity at the CIEMAT RF power laboratory facilities, installed at the BTESA company. The performance exceeded anything obtained to date in the market.