This paper demonstrates the feasibility and very good performance of a kilowatt-level power amplifier in a single-ended architecture, intended for energy systems. The prototype is designed at 352 MHz for the ESS LINAC and delivers up to 1250 W with 71% efficiency in pulsed operation with a duty cycle of 5%, 3.5 ms pulse at 14 Hz repetition.Introduction: Solid-state r.f. high power amplifiers (PA) are increasingly used as energy systems in particle accelerators, such as cyclotrons and LINACs, in a large variety of applications, including radionuclide production, particle therapy for cancer treatment, and synchrotron light sources for scientific studies [1][2]. The design of solid-state PA for energy systems calls for a different approach than the design of PA for data transmission, where linearization is paramount. PA as energy systems could be operated in saturation and therefore be more efficient, while delivering more output power [3]. A direct implication is the reduction of the number of amplifier modules, as relatively more power, more efficiently could be delivered per module.It remains unclear whether a simple architecture could be adopted at the kilowatt-level. In order to improve the competitiveness of solid state based energy systems, a simple architecture could drastically reduce the manufacturing costs, as a high number of modules need to be combined.The purpose of this letter is to demonstrate by simulations and experimentation, the feasibility and performance of a single-ended power amplifier at kilowatt-level, realized in a planar printed circuit board technology and avoiding using complex circuits, such as baluns, as is presently customary at these high power levels [4].

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This paper presents the first results of an in-house developed low-level radio frequency (LLRF) system and a 10 kW solid state power amplifier (SSPA). The design approach for the SSPA is based on eight resonant single-ended kilowatt modules combined using a planar Gysel combiner. Each of the single-ended modules is based on a two-stepped impedance resonant matching, allowing for harmonic suppression, simple design for massive production, and high-performance design. A design methodology to tune SSPA modules for optimum combining efficiency is presented thoroughly in the time domain. We characterize the power droop due to capacitor banks in the time domain. In open loop of compensation, it is about 1 kW within the pulse of peak value 10 kW and a duration of 3.5 ms. This may lead to the beam instability of the accelerator as particles are not provided with the same energy during the pulse. By incorporating our LLRF system, it is demonstrated that the objective of amplitude and phase stability is satisfied, as required in the European Spallation Source proton accelerator. The presented design also offers the advantages of compact form factor, low complexity, and better performance. In closed loop compensation, the variation of amplitude (pulse droop) is measured on the order of 20 W, which is equivalent to 0.2% at 10 kW peak output power.

In this paper, a methodology for designing quasi-time optimal cascade controller for ball and beam system is presented and the result is compared with LQR method as well as implemented on real system. Ball and beam system is a highly non-linear system, its parameters are difficult to estimate accurately and easily affect by disturbance. In designed method, a mathematical model describing the system is built, including a motor that creates a rotation of beam and is divided into two subsystems when synthesizing the cascade controller for the system. The first floor is the beam subsystem with the output is the angle as the set value for the second floor, which is ball subsystem. The controller is synthesized for each subsystem based on the quasi-time optimal control. The advantage of this method is the synthesizing control law with non-linear system. The simulation results show the effectiveness of the proposed design.