Linearized Field Theory of a Smith–Purcell Traveling Wave Tube

Freund, H.P.; Abuelfadl, Tamer M.

doi:10.1109/tps.2004.827612

Cited by 53 publications

(19 citation statements)

References 14 publications

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“…The questions we are concerned with were not investigated in that work. We mention also the recent analytic work of Freund and Abu-Elfadi on the Smith-Purcell traveling-wave tube [16], which resembles that of Andrews and Brau, except that there is a second conducting plane parallel to the grating. While the analysis of the coupling of beam and structure modes is similar, the presence of the second conductor means that radiation occurs only in the forward and backward directions, and the possibility of coherent SP radiation at a particular angle is lost.…”

Section: Introductionmentioning

confidence: 94%

Simulation of Smith-Purcell radiation using a particle-in-cell code

Donohue

Gardelle

2005

Phys. Rev. ST Accel. Beams

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A simulation of the generation of Smith-Purcell (SP) radiation at microwave frequencies is performed using the two-dimensional particle-in-cell code MAGIC. The simulation supposes that a continuous, thin (but infinitely wide), monoenergetic electron beam passes over a diffraction grating, while a strong axial magnetic field constrains the electrons to essentially one-dimensional motion. The code computes the time-dependent electric and magnetic fields by solving the Maxwell equations using a finite element approach. We find that the passage of the beam excites an evanescent electromagnetic wave in the proximity of the grating, which in turn leads to bunching of the initially continuous electron beam. The frequency and wave number of the bunching are determined, and found to be close to those proposed by Brau and co-workers in recent work. This frequency is below the threshold for SP radiation. However, the bunching is sufficiently strong that higher harmonics are clearly visible in the beam current. These harmonic frequencies correspond to allowed SP radiation, and we see strong emission of such radiation at the appropriate angles in our simulation, again in agreement with Brau's predictions. We also find that at the ends of the grating, some of the evanescent wave is diffracted away from the surface, and radiation below the threshold occurs. In addition, we observe a second evanescent wave at the same frequency, but with a different wave number. The existence of this wave is also predicted by the theory, although its presence in our simulation is unexpected. Numerical estimates of the growth of the evanescent wave are also in reasonable agreement with the predictions, although the precise form of the dependence of the gain on beam current remains hard to establish.

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Section: Introductionmentioning

confidence: 94%

Simulation of Smith-Purcell radiation using a particle-in-cell code

Donohue

Gardelle

2005

Phys. Rev. ST Accel. Beams

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“…The coupling via the longitudinal beam perturbation is weakened by decreasing B 0 as pointed out in Ref. 8. On the other hand, the transverse beam perturbation, i.e., the modulation of beam surface dominates the Cherenkov interaction in the low magnetic field region [15].…”

Section: Discussionmentioning

confidence: 75%

“…In a pioneering work of the Ledatron, parallel-plate SWS was called Fabry-Perot resonator [7]. Recently, surface waves and SP traveling wave tube operation of the parallel-plate SWS have been studied in a frequency range around 100 GHz (W-band) [8]. Since cylindrical BWOs are suitable for high-power operations, it is important to study the surface waves of coaxial SWS in such high frequency ranges in order to realize high-power and highfrequency EM wave sources.…”

Section: Introductionmentioning

confidence: 99%

Surface Waves in Oversized G-Band Slow-Wave Structures with Rectangular Corrugations

Ogura

Kojima

Kawabe

et al. 2014

Plasma and Fusion Research

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Surface waves in oversized G-band slow-wave structure with rectangularly corrugated wall are analyzed numerically. The inner corrugation generates cylindrical surface wave. The outer corrugation also generates transverse magnetic surface wave. The upper cut-offs of surface waves are controlled by corrugation amplitude. In excitation of the surface waves by an annular electron beam, the slow cyclotron interaction as well as the Cherenkov interaction occur due to there-dimensional beam perturbations. The slow cyclotron interaction merges with the Cherenkov interaction at lower magnetic field. The merged growth rate is enhanced by 13 % as compared to the isolated Cherenkov growth rate. The surface waves on inner and outer corrugations can have different frequencies and can be excited selectively by adjusting the beam radius of the electron beam.

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“…In recent years, there are renewed interests in the Smith-Purcell (SP) radiation [1][2][3][4][5][6][7], since it is a promising alternative in the development of the THz sources [8][9][10]. It is well known that the SP radiation is emitted when an electron passes over a periodic metallic grating [11].…”

Section: Introductionmentioning

confidence: 99%