Theoretical and simulation study of ‘Comb’ electron beam and THz generation

Joshi, V.; Lehnert, U.; Karmakar, J.; Kumar, N. V. Narendra; Karmakar, B.; Tripathi, Sumit; Aryshev, Alexander; Ghosh, Subhendu; Urakawa, J.; Bhandari, R.K.; Kanjilal, D.

doi:10.1016/j.nima.2018.10.072

Cited by 5 publications

(4 citation statements)

References 85 publications

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“…However, the fully bunched electron beam is challenging to be obtained in the experiment. In practice, the techniques based on photocathodes can be used to form such a beam [44]. In this paper, a section of the cylindrical grating is utilized to prebunch the DC electron beam to further facilitate the feasibility of the concept.…”

Section: Discussionmentioning

confidence: 99%

A Terahertz Vortex Beam Emitter With Tunable Topological Charge and Harmonic Excitation

Zhang

Zhu

et al. 2021

J. Lightwave Technol.

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Terahertz (THz) vortex beams carrying orbital angular momentum (OAM) with high purity and tunable topological charge (TC) will undoubtedly bring extraordinary capacities for advanced imaging or communication systems. We propose a convenient and efficient method to generate a tunable and broadband vortex beam that is excited by superradiant Smith-Purcell radiation (SSPR) on a helical grating. This scheme fully explores the advantages of natural broadband evanescent wave carried by the electron beam and the Bloch's theorem regulated helical periodic systems. An explicit relation is established between the index of the spatial harmonic wave on the grating and the topological charge of the vortex beam. The electron energy in the SSPR can be customized to ignite the specific spatial harmonics and manipulate the OAM beam, accordingly. The separated radiation region also promises the high purity of the OAM spectrum. The harmonic excitation reduces the communality between the wavelength and the device size and alleviates the difficulty of device fabrication in the THz band. The proposed vortex scheme can not only be handily scaled to microwave and mid-infrared regions, but also bring possibilities to applications based on compact tunable vortex beam sources.

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Section: Discussionmentioning

confidence: 99%

A Terahertz Vortex Beam Emitter With Tunable Topological Charge and Harmonic Excitation

Zhang

Zhu

et al. 2021

J. Lightwave Technol.

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“…Bunched beam superradiance is an attractive concept for attaining intense THz radiation in a compact FEL scheme [1,3,[14][15][16]]. Here we presented theory and design consideration of a superradiant waveguide FEL based on a compact (60 cm long) hybrid photocathode RF gun.…”

Section: Discussionmentioning

confidence: 99%

Theory and design consideration of a THz superradiant waveguide FEL

Weinberg,

Gover,

Nause

et al. 2024

Front. Phys.

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We present theoretical analysis and design considerations of a THz superradiant FEL. We derive analytical expressions for the spectral parameter of THz radiation, emitted superradiantly in a rectangular waveguide using a Longitudinal Section Magnetic mode expansion. The results compare well with numerical simulations using UCLA GPTFEL code. GPT simulations of the accelerator e-beam transport show that the chirp provided by a hybrid photocathode RF gun, can produce tight bunching at the undulator site below σ = 100fs. This enables intense superradiant emission up to 3THz, limited by the beam bunching factor. Phase-space analysis of the beam transport indicates that keeping the beam bunching parameter small enough for higher THz frequency operation is limited by the energy spread of the beam in the gun.

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“…Figure 2 shows the radiation frequencies that can be generated from U48 in the electron energy range of 4-8 MeV. The beam optics studies for the system have been done earlier [4,5] using codes ASTRA [6] and General Particle Tracer (GPT) [7].…”

Section: Introductionmentioning

confidence: 99%

Compensation scheme for non-linear beam defocusing inside planar undulator

et al. 2021

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The Delhi Light Source (DLS), is a compact THz facility based on the principle of pre-bunched FEL, which is at the commissioning stage at Inter University Accelerator Centre (IUAC), New Delhi. The facility will produce relativistic electron beam in the energy range 4 to 8 MeV to generate THz radiation in the range 0.18–3.0 THz. To study the effect of the undulator U48 on this low energy range of the electron beam, a 3D field map of U48 was generated with the help of measured magnetic field data. Beam tracking simulations were performed with the generated field map at the minimum gap of U48. Simulations showed that the quadrupole component of the transverse field roll-off, which is the dominant component within the width of the vacuum chamber can introduce a substantial growth of the beam size in the wiggling plane and result in severe beam loss while propagating through the vacuum chamber inside the undulator. To compensate the dynamic quadrupolar field, an extended quadrupole field correction coil was implemented in the simulation by superimposing its field on the magnetic field of U48. Such a correction scheme showed a remarkable improvement to contain the beam transverse growth.

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Theoretical and simulation study of ‘Comb’ electron beam and THz generation

Cited by 5 publications

References 85 publications

A Terahertz Vortex Beam Emitter With Tunable Topological Charge and Harmonic Excitation

A Terahertz Vortex Beam Emitter With Tunable Topological Charge and Harmonic Excitation

Theory and design consideration of a THz superradiant waveguide FEL

Compensation scheme for non-linear beam defocusing inside planar undulator

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