scholarly journals A new concept for the collection of an electron beam guided by an externally applied magnetic field

Author(s):  
I.G. Pagonakis ◽  
J.-P. Hogge ◽  
S. Alberti ◽  
K.A. Avramides ◽  
J.L. Vomvoridis
2019 ◽  
Vol 33 (14n15) ◽  
pp. 1940008
Author(s):  
Yi Sheng Yeh ◽  
Cong-Yuan Zheng ◽  
Li-Jhen Li ◽  
Po-Yi Chiang ◽  
Yen-Cheng Chen ◽  
...  

Terahertz (THz) gyrotrons can operate with a lower applied magnetic field in harmonic operation, but the weakened harmonic interactions in harmonic gyrotrons can introduce serious challenges when mode competition occurs. The use of an axis-encircling electron beam can greatly alleviate mode competition in a harmonic gyrotron. In this paper, we study axial modes for third-harmonic [Formula: see text]-mode large-orbit gyrotrons. Simulation results reveal that the minimum current for oscillation to begin in each axial mode in the gyrotron regime is associated with a specific range of applied magnetic field. To avoid mode competition, tapered applied magnetic fields and waveguide radii are employed to enhance the high-order axial modes and suppress the low-order axial modes. Furthermore, spurious transverse modes in a THz gyrotron are discussed below. A stable third-harmonic [Formula: see text]-mode large-orbit gyrotron at the third-order axial mode is predicted to yield peak output power of 6.5 kW at 768.1 GHz with an efficiency of 10% for a 75-kV, 0.85-A electron beam with an axial velocity spread of 3%.


2017 ◽  
Vol 83 (2) ◽  
Author(s):  
Toshihiro Taguchi ◽  
Thomas M. Antonsen ◽  
Kunioki Mima

Relativistic electron beam transport through a high-density, magnetized plasma is studied numerically and theoretically. An electron beam injected into a cold plasma excites Weibel and two-stream instabilities that heat the beam and saturate. In the absence of an applied magnetic field, the heated beam continues to propagate. However, when a magnetic field of particular strength is applied along the direction of beam propagation, a secondary instability of off-angle whistler modes is excited. These modes then couple nonlinearly creating a large amplitude parallel-propagating whistler that stops the beam. Here, we will show these phenomena in detail and explain the mechanism of whistler mediated beam stagnation.


Author(s):  
D. E. Speliotis

The interaction of electron beams with a large variety of materials for information storage has been the subject of numerous proposals and studies in the recent literature. The materials range from photographic to thermoplastic and magnetic, and the interactions with the electron beam for writing and reading the information utilize the energy, or the current, or even the magnetic field associated with the electron beam.


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