Forward Wave Amplification Enhanced Radiation in a 1 THz Harmonic Gyrotron

Among the most promising terahertz (THz) radiation devices, gyrotrons can generate powerful THz-wave radiation in an open resonant structure. Unfortunately, such an oscillation using high-Q axial mode has been theoretically and experimentally demonstrated to suffer from strong ohmic losses. In this paper, a solution to such a challenging problem is to include a narrow belt of lossy section in the interaction circuit to stably constitute the traveling wave interaction (high-order-axial-mode, HOAM), and employ a down-tapered magnetic field to amplify the forward-wave component. A scheme based on the traveling-wave interaction concept is proposed to strengthen electron beam-wave interaction efficiency and simultaneously reduce the ohmic loss in a 1-THz third harmonic gyrotron, which is promising for further advancement of high-power continuous-wave operation.