Beam conditioning for electron energy recovery systems in devices employing axis-encircling beams

Depressed collectors are extensively used in linear-beam devices. In spiralling beam devices, the motion of the spent beam needs to be converted into axial motion before it can deliver energy to the retarding axial electrostatic field produced by depressed collectors. A method of doing so is presented here, along with simulation results. A large-orbit gyrotron is chosen as an illustrative example in which the axis-encircling beam is generated by passing an axially streaming beam through a magnetic cusp. After rf interaction, an ‘unwinding’ of the beam is done by a second magnetic cusp with a reversed magnetic field. The trajectories of electrons going through the two cusps have been simulated in order to evaluate the effects of finite cusp width and finite width of emitting surface. Also studied are the effects of variations of the magnetic field, the accelerating voltage of the beam, and the distance between cusps. These simulations show that the rotational energy of electrons is largely converted into a...

[1]  W. Destler,et al.  High-Power Microwave Generation from a Large-Orbit Gyrotron in Vane and Hole-and-Slot Conducting Wall Geometries , 1985, IEEE Transactions on Plasma Science.

[2]  D. Arnush,et al.  Design of a high power CW free electron maser , 1982 .

[3]  R. True,et al.  Emittance and the design of beam formation, transport, and collection systems in periodically focussed TWT's , 1987, IEEE Transactions on Electron Devices.

[4]  H.G. Kosmahl,et al.  Modern multistage depressed collectors—A review , 1982, Proceedings of the IEEE.

[5]  Yue Ying Lau,et al.  Theory of a low magnetic field gyrotron (gyromagnetron) , 1982 .

[6]  W. Namkung,et al.  Studies of microwave radiation from a low‐energy rotating electron beam in a multiresonator magnetron cavity , 1987 .

[7]  W. Namkung,et al.  Linear theory of cusptron microwave tubes , 1984 .

[8]  W. W. Destler,et al.  Relativistic electron dynamics in a cusped magnetic field , 1974 .

[9]  W. W. Destler,et al.  High-power microwave generation from large-orbit devices , 1988 .

[10]  Victor L. Granatstein,et al.  High average power and high peak power gyrotrons: present capabilities and future prospects† , 1984 .

[11]  William B. Herrmannsfeldt,et al.  ELECTRON TRAJECTORY PROGRAM , 1979 .

[12]  R. Grow,et al.  Impedance calculations for travelling wave gyrotrons operating at harmonics of the cyclotron frequency in magnetron-type circuits , 1982 .

[13]  W. Lawson,et al.  The design of a small‐orbit/large‐orbit gyroklystron experiment , 1987 .

[14]  S. A. Malygin,et al.  The problems of increase in power, efficiency and frequency of gyrotrons for plasma investigations , 1984 .

[15]  G. Scheitrum,et al.  A triple pole piece magnetic field reversal element for generation of high rotational energy beams , 1981, 1981 International Electron Devices Meeting.

[16]  W. Destler,et al.  Radial and axial compression of a hollow electron beam using an asymmetric magnetic cusp , 1977 .