Abstract
Radio frequency Ohmic loss due to non-ideal conductor boundaries seriously limits the performance of electronic devices. In this paper, the Ohmic losses of two simple models are calculated by particle-in-cell (PIC) simulation, which is also verified by theoretical calculation. Thereafter, based on PIC simulation, we have studied the variation of the Ohmic losses of relativistic backward wave oscillators (RBWOs) with operating frequency and material conductivity. The PIC simulation results show that as the frequency advances, the Ohmic losses of RBWOs deteriorate sharply. The power loss becomes non-negligible when compared with the output power. The loss-power ratio of a V-band RBWO made of stainless steel is over 25%. The non-negligible Ohmic loss can explain to some extent that the difference between the simulated and the experimental output power of the RBWO becomes apparent as the working frequency increases.
Highlights
Radio frequency (RF) Ohmic loss induced by limited conductivity may bring out the decrease in output power and frequency detuning and seriously limits the performance of electronic devices.1–7 In the field of RF accelerators, the presence of Ohmic loss may cause frequency detuning of the accelerating cavities because of high Q factors and eventually affect the stability of the bunch.8,9 superconducting cavities made of niobium have been proposed to suppress power loss due to finite conductivity effectively, and high acceleration gradients have been acquired within little power injection.10,11 The skin depth of the electromagnetic waves in the terahertz devices is equivalent to the mechanical accuracy
It has been revealed that even using copper, the output power of a surface wave oscillator operating in the TM01 mode with a working frequency of 0.377 THz attenuates by more than half compared with the perfect electric conductor (PEC)
As the frequency advances to the millimeterwave band, the Ohmic loss due to non-ideal conductor boundaries will deteriorate sharply, the power loss becomes non-negligible when compared with the output power
Summary
Radio frequency (RF) Ohmic loss induced by limited conductivity may bring out the decrease in output power and frequency detuning and seriously limits the performance of electronic devices. In the field of RF accelerators, the presence of Ohmic loss may cause frequency detuning of the accelerating cavities because of high Q factors and eventually affect the stability of the bunch. superconducting cavities made of niobium have been proposed to suppress power loss due to finite conductivity effectively, and high acceleration gradients have been acquired within little power injection. The skin depth of the electromagnetic waves in the terahertz devices is equivalent to the mechanical accuracy. It has been revealed that even using copper, the output power of a surface wave oscillator operating in the TM01 mode with a working frequency of 0.377 THz attenuates by more than half compared with the perfect electric conductor (PEC).. The Ohmic loss has not been paid enough attention in the design of high-power microwave (HPM) generators owing to their low cavity Q-factors (∼100), especially for relativistic backward wave oscillators (RBWOs). As the operating-frequency increases, the size of RBWO shrinks proportionally, resulting in the strength of the electromagnetic fields to enhance correspondingly. The Ohmic loss may limit the development of the higher power output and affect the stability and reliability of RBWOs. The accumulation of power losses may increase the background temperature of the devices, intensify the field-induced electron emission on the metal surfaces, and aggravate the RF breakdown during repetitive frequency operation..
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