Time domain characterization of high power solid state amplifiers for the next generation linear accelerators

Abstract

AbstractThis paper presents the time‐domain characterization of high power pulsed solid state amplifiers to be used for linear accelerator applications. The study comprises nonlinear circuit envelope simulations and time domain envelope measurements. Measurements and simulations are performed under the pulsed conditions (3.5 ms pulse width, 5% duty cycle) specific to the European Spallation Source (ESS) high intensity proton accelerator. We measure the characteristics of pulsed LDMOS based power amplifiers such as: pulse droop along the pulse, efficiency, average envelope pulse amplitude and phase, pulse drain current waveform, pulse drain voltage waveform, etc. A comparison between the measured results and the simulated results is also presented. In addition to the pulse profile characterization, the pulse to pulse (P2P) stability of the presented solid state power amplifier (SSPA) is investigated as variations of amplitude and phase. The P2P stability simulations are introduced as a combination of the Monte‐Carlo simulations and the nonlinear circuit envelope simulations. The simulated results are used for fitting the P2P measurements to give an early insight of causes of instabilities of the nonlinear LDMOS models.