Electron beam requirements for a three-dimensional Smith-Purcell backward-wave oscillator for intense terahertz radiation

Kim, Kwang-Je; Kumar, Vinay

doi:10.1103/physrevstab.10.080702

Cited by 36 publications

(4 citation statements)

References 22 publications

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“…The decrease in SPR power for increasing grating period were in the same trend for both simulation and measurement results. This scenario can be explained by the numerical result of radiation amplitude introduced by [55]. The consistency of detected SPR powers when using different grating periods, formulated by CST simulation, our experiment, and previous numerical calculation, can be established as a verification of SPR detection without need of spectrally-resolved detection system.…”

Section: Alternative Technique For Verification Of Thz-sprsupporting

confidence: 53%

An alternative technique for verification of terahertz Smith–Purcell radiation

Rattanawan¹,

Chulapakorn²,

Tanapirom³

et al. 2021

J. Phys. D: Appl. Phys.

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An alternative technique to verify terahertz (THz) Smith-Purcell radiation (SPR) was proposed by using different grating periods. A compact DC electron gun, serving as a THz source, was modified to generate continuous 35 keV electron beam that passes by a metal-coated silicon grating in order to induce SPR. A design on beam optics to generate high-brightness beam was carried out by using Computer Simulation Technology (CST) Studio Suite ® software package. The optimization of beam parameters was obtained and experimentally performed. Results show that the root-mean-square (rms) beam size (diameter) is about 1 mm when supplying beam current of 200 µA, and rms beam emittance is about 3π mm mrad. The CST simulation software was, furthermore, employed to observe radiation spectra when using different grating structures. A liquid-helium cooled silicon bolometer together with a low-pass filter was used to detect radiation power. The results reveal that incoherent THz signal with power of 1.5 µW cm −2 is observed when the continuous-beam current is about 200 µA. The dependence of THz frequency and power on the grating period, that is associated to the SPR, was also investigated in this work.

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Section: Alternative Technique For Verification Of Thz-sprsupporting

confidence: 53%

An alternative technique for verification of terahertz Smith–Purcell radiation

Rattanawan¹,

Chulapakorn²,

Tanapirom³

et al. 2021

J. Phys. D: Appl. Phys.

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“…Since all the grating widths are finite, several theories have been proposed to study coherent SPR in three dimensions. Kumar 4 et al extended their previous analysis to 3D and provided estimation of the beam parameters and minimum current, which is similar to the Dartmouth terahertz experiments. 5 Andrews 6,7 et al derived a 3D dispersion relation for a lamellar grating with sidewalls, as reported by Li 8 et al The axial magnetic field in this theory is assumed to be zero.…”

Section: Introductionmentioning

confidence: 86%

Three-dimensional theory of Smith-Purcell free-electron laser with dielectric loaded grating

Cao

Liu

Wang

et al. 2014

Journal of Applied Physics

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A dielectric loaded rectangular grating for Smith-Purcell devices is proposed in this paper. Regarding the electron beam as a moving plasma dielectric, a three dimensional (3D) linear theory of beam-wave interaction is developed. The first and second order growth rates are calculated, which are obtained by expanding hot dispersion equation at synchronous point. The results show that the cutoff frequency is affected by grating width. The dispersion curve becomes flatter and shifts towards lower frequency by loading dielectric in grooves. The simulation results, which are obtained by a 3D particle-in-cell code, are in good agreement with theoretical calculations. Compared the first and second order growth rate, it shows that the discrepancy is large when beam parameters are selected with high values. In this case, it is necessary to apply the second order growth rate, which can accurately describe the process of beam-wave interaction.

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“…This technique was proposed as a way of producing a high-aspect-ratio beam to mitigate beamsstrahlung in future linear colliders while also circumventing the use of an electron damping ring conventionally used to reduce the vertical emittance (Brinkmann et al, 2001). Likewise, the technique was also adapted for applications in of microwave-and THz-radiation generation (Carlsten and Bishofberger, 2006;Kim and Kumar, 2007) using, e.g., the concept of Smith-Purcell backward oscillator (Andrews et al, 2005).…”

Section: Decoupling Of Cam-dominated Beams and Transverse Emittance P...mentioning

confidence: 99%

Bunch Shaping in Electron Linear Accelerators

Ha,

Kim,

Piot

et al. 2021

Preprint

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Modern electron linear accelerators are often designed to produce smooth bunch distributions characterized by their macroscopic ensemble-average moments. However, an increasing number of accelerator applications call for finer control over the beam distribution, e.g., by requiring specific shapes for its projection along one coordinate. Ultimately, the control of the beam distribution at the single-particle level could enable new opportunities in accelerator science. This review discusses the recent progress toward controlling electron beam distributions on the "mesoscopic" scale with an emphasis on shaping the beam or introducing complex correlations required for some applications. This review emphasizes experimental and theoretical developments of electron-bunch shaping methods based on bounded external electromagnetic fields or via interactions with the self-generated velocity and radiation fields. 1. Space-charge field with a single bunch 41 2. Space-charge field with a few bunches 43 3. Space-charge field with multiple bunches: space-charge oscillation 44 4. Space-charge field with multiple bunches: longitudinal cascade amplifier 46 5. Space-charge field with multiple bunches: plasma cascade amplifier 47 B. Shaping profiles using coherent synchrotron radiation 47 C. Shaping profiles using wakefields 49 1. Bunch compression 50 2. Bunch train generation 50 3. Single-bunch profile shaping 51 4. Control over the energy distribution 52 5. Control over longitudinal phase space 53 VI. Coupling between degrees of freedom for phase-space tailoring 54 A. Introduction 54 B. Coupling between the two transverse degrees of freedom 54 1. Producing beams with canonical angular momentum 54 2. Decoupling of CAM-dominated beams and transverse emittance partitioning 55 3. Phase-space exchange between the two transverse planes 57 C. Transverse-to-longitudinal phase-space exchangers 59 1. Emittance exchange 59 2. Current profile shaping 60 3. Bunch compression 62 4. Double phase-space exchangers 62 D. Generalized phase-space repartitioning between the three degrees of freedom 65 1. Flat beam transformation combined with emittance exchange 65 2. Coupling between the longitudinal and transverse phase spaces 65

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Electron beam requirements for a three-dimensional Smith-Purcell backward-wave oscillator for intense terahertz radiation

Cited by 36 publications

References 22 publications

An alternative technique for verification of terahertz Smith–Purcell radiation

An alternative technique for verification of terahertz Smith–Purcell radiation

Three-dimensional theory of Smith-Purcell free-electron laser with dielectric loaded grating

Bunch Shaping in Electron Linear Accelerators

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