Relativistic performance analysis of a high current density magnetron injection gun

Abstract

Electron beam quality is essential to the performance of millimeter-wave gyroamplifiers, particularly the gyrotron traveling-wave tube amplifier, which is extremely sensitive to the electron velocity spread and emission uniformity. As one moves up in power and frequency, the quality of the electron beam becomes even more critical. One aspect of the electron beam formation technology which has received relatively little attention has been the performance analysis of the electron beam itself. In this study, a 100 kV, 8 A magnetron injection gun with a calculated perpendicular-to-parallel velocity ratio of 1.4 and axial velocity spread of 3.5% has been designed, tested, and analyzed. It is shown that the equipment precision and a fully relativistic data analysis model afford sufficient resolution to allow a verification of the theoretical predictions as well as a quantitative inference to the surface roughness of the cathode used.

Magnetron Injection Gun for High-Power Gyroklystron

“…Nanosized-scandia-doped dispenser cathodes with such high current density has been reported with more than 5000 hours lifetime [22]. A MIG with a current density of 30 A/cm 2 using a SpectraMat 612X scandate cathode has been designed and tested [23]. Other parameters such as the magnetic field compression ratio, and the maximum electric field were chosen as 22.5 and 7 kV/mm.…”

Helical Electron Beam Status Online Evaluation for Magnetron Injection Gun

“…Numerous articles have also reported experimental measurements pertaining to beam characteristics such as the beam pitch factor α, transverse velocity spread ∆β ⊥ , stability, and concentricity. UC Davis has introduced an axial energy beam analyzer to test α and axial velocity spread in the gyro-TWT [24]. At IAP-RAS, investigations into the velocity spread and the oscillatory energy of trapped electrons have been conducted, with results indicating a significant impact on beam parameters [25].…”

Design and Simulation Analysis of a Magnetron Injection Gun for a 0.42 THz Second Harmonic Gyrotron

“…The source of electrons is usually a magnetron injection gun (MIG) [9][10][11] in gyrotron, which generate annular electron beams in which electrons execute small cyclotron orbits at a frequency required for cyclotron resonance interaction with RF waves. The external magnetic field is responsible to focus the electron beam with required beam properties in the interaction region; magnetic field guides the electron beam from the point of emission up to its collection.…”