Numerical Study of Instabilities Induced by Sheet Electron Beam on Corrugated Metal Plate

Watanabe, Osamu; Watanabe, Tsuguhiro; Ogura, K.; Tatematsu, Y.; Shima, Y.; Imai, T.

doi:10.1143/jjap.46.6051

Cited by 4 publications

(5 citation statements)

References 48 publications

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“…However, a sufficient depth of the corrugation is necessary for this mode to exist. In the case where H/L < 1/4, where H and L are the corrugation amplitude and the period length, respectively, the electromagnetic surface wave on the corrugation becomes an evanescent wave [1,7,8].…”

Section: Introductionmentioning

confidence: 99%

Measurements of electromagnetic surface wave propagation in the cut‐off frequency region

Watanabe

2013

IEEJ Transactions Elec Engng

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Electromagnetic surface wave propagation on a corrugated metal plate is confirmed by a cold test in the X‐band. The measured cut‐off frequency is almost in agreement with the theoretical cut‐off frequency. The propagation is damped at a frequency region higher than the cut‐off frequency. The periodicity of the propagation power to the frequency is confirmed. For the confirmation of these characteristics, it is necessary that the corrugated metal plate is enclosed within a microwave absorber. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

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Section: Introductionmentioning

confidence: 99%

Measurements of electromagnetic surface wave propagation in the cut‐off frequency region

Watanabe

2013

IEEJ Transactions Elec Engng

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“…This mechanism is known as Smith-Purcell free-electron laser (SP-FEL) [3]. Absolute and convective instabilities of SPR interaction were studied in [4].…”

Section: Introductionmentioning

confidence: 99%

Smith-Purcell radiation from a charge moving above a grating of finite length and width

Kesar

2010

Phys. Rev. ST Accel. Beams

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Smith-Purcell radiation (SPR), emitted when a charge passes above a periodic grating, is important for applications such as terahertz production and nondestructive bunch-length diagnostics. The grating width is shown to become an important parameter for accurately predicting the radiation, and especially in the highly relativistic regime where the charge wakefield considerably stretches in the transverse direction. The SPR radiation is rigorously calculated by the electric-field integral equation (EFIE) method for a grating of finite width and length. The integral equation is arranged as a multilevel block-Toeplitz matrix by using symmetry under translation with respect to the grating period and width directions. Following Barrowes et al. [Microw. Opt. Technol. Lett. 31, 28 (2001)] enhanced computational efficiency can be achieved by matrix to vector projection of the essential matrix elements. A numerical example is calculated for a relativistic ( ¼ 36), 1-mm long, bunch traveling 0.6-mm above a ten-period grating with a period of 2.0 mm and width of 10 mm. The SPR resonance relationship and its broadening due to the finite number of grooves are consistent with the closed-form formulations. The surface current was shown to be concentrated along the center of the grating and decreasing towards its edges. The surface current, power spectrum, and radiated energy were compared to the EFIE formulation in which an infinitely wide grating was assumed. The above parameters resulted in considerable difference of up to a factor of 2.5 between the finite width and the infinitely wide grating assumption, which means that for accurate calculations the grating width should be taken into consideration. A general rule for the required grating width to achieve an accurate SPR radiation result relative to the infinite width result, and the expected accuracy by the infinite width assumption for most radiation angles, is provided.

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“…A reflector is not required. The SWO oscillates by Cherenkov instability between the SWM and a slow space charge mode (SSCM) 2. Thus, the output power can be increased by decreasing the distance between the beam and the plate, and/or by expanding the interaction region, which is the plate.…”

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“…A dispersion equation based on these boundary conditions was already derived in 2. The components of Maxwell equation are defined by two vector components, based on the ∇ · B = 0.…”

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Numerical study of the oscillation characteristics of a surface wave oscillator

Watanabe

2010

IEEJ Transactions Elec Engng

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The oscillation characteristics of a surface wave oscillator is analyzed numerically. The oscillation frequency due to Cherenkov instability can be controlled by the electron beam energy though the alteration of the accompanying temporal growth rate. The growth rate increases exponentially with the proximity of the beam to a corrugated metal plate. The oscillation frequency is not changed by this proximity. The peak of the growth rate of the Cherenkov instability is one or more orders higher than that of a Smith-Purcell type instability. Moreover, in frequency and wavenumbers, the difference of two instabilities is enlarged by the increase in the growth rate. Therefore, the influence of the Smith-Purcell type instability on the Cherenkov instability is decreased. 

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Numerical Study of Instabilities Induced by Sheet Electron Beam on Corrugated Metal Plate

Cited by 4 publications

References 48 publications

Measurements of electromagnetic surface wave propagation in the cut‐off frequency region

Measurements of electromagnetic surface wave propagation in the cut‐off frequency region

Smith-Purcell radiation from a charge moving above a grating of finite length and width

Numerical study of the oscillation characteristics of a surface wave oscillator

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