Amplification of Picosecond Pulses with a Photonic-Band-Gap Gyro-TWT

We report the amplification of 250 GHz pulses as short as 150 ps without observation of pulse broadening using a photonic-band-gap (PBG) gyrotron traveling-wave-amplifier. The gyrotron amplifier operates with 38 dB of device gain and 8 GHz of instantaneous bandwidth. The operational bandwidth of the amplifier can be tuned over 16 GHz by adjusting the operating voltage of the electron beam and the magnetic field. The amplifier uses a 30 cm PBG interaction circuit to confine the desired TE03 operating mode while suppressing lower order modes which can result in undesired oscillations. The circuit gain is >55 dB for a beam voltage of 23 kV and a current of 700 mA. These results demonstrate the wide bandwidths and high gain achievable with gyrotron amplifiers.