Design and experimental results are presented from two high power microwave generation experiments utilizing a high repetition rate induction linac generated electron beam. A relativistic klystron has generated more than 100 MW microwave pulses in X-band for 50 ns without pulse shortening or breakdown. Design studies for the first cyclotron autoresonance maser (CARM) amplifier using an inductio...

Context. A selection of ultracool dwarfs are known to be radio active, with both gyrosynchrotron emission and the electron cyclotron maser instability being given as likely emission mechanisms. Aims. We explore whether ultracool dwarfs previously undetected at 8.5 GHz may be detectable at a lower frequency. Methods. We select a sample of fast rotating ultracool dwarfs with no detectable radio a...

The Very Large Array was used to observe the ultracool rapidly rotating M9 dwarf TVLM 513-46546 simultaneously at 4.88 GHz and 8.44 GHz. The radio emission was determined to be persistent, variable and periodic at both frequencies with a period of ∼ 2 hours. This periodicity is in excellent agreement with the estimated period of rotation of the dwarf based on its v sin i of ∼ 60 km s. This rota...

Cyclotron harmonic interactions are a key physics issue of critical importance to the generation of terahertz radiation via the electron cyclotron maser instability for practical magnetic field strengths. We present an inherent mechanism, as well as a deciding factor, which governs the competition between low- and high-harmonic interactions. Multimode simulations reveal the physical process in ...

Auroral kilometric radiation (AKR) is the paradigm of intense radio emission from planetary magnetospheres. Being close to electron gyro frequency and/or its lower harmonics, observation indicates non-thermal state source plasma. Emission produced when plasma enters a energetic excitation which results in deformation distribution function. Under certain conditions this leads "quasi-coherent" em...

A cyclotron-resonance maser (CRM) is implemented in a periodic quadrupole waveguide. The device oscillates at the fundamental and high harmonics of the cyclotron frequency. This CRM employs a tenuous low-energy electron beam ( approximately 10 keV, 0.2 A). The periodic structure consists of an array of disks along the quadrupole transmission line, hence it combines both azimuthal and axial peri...