| Paper | Title | Page |
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| WEP086 | Capabilities of Terahertz Super-Radiance from Electron Bunches Moving in Micro-Undulators | 517 |
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Funding: This work was supported by the Israeli Ministry of Science, Technology and Space and by the Russian Foundation for Basic Research, grant No. 16-02-00794. An available frequency range of coherent radiation from ps bunches with high charge and moderate particle energy significantly enhances if one uses a micro-undulator with a high transverse field. Such an undulator can be implemented by redistributing a strong uniform magnetic field by a helical ferromagnetic or copper insertion. According to simulations and experiments with prototypes, a steel helix with a period of (8-10) mm and an inner diameter of (1.5-2) mm inserted in the 3T-field of solenoid can provide an undulator field with an amplitude of 0.6 T. Using a hybrid system with a permanently magnetized structure can increase this value up to 1.1 T. The necessary steel helices can be manufactured on the machine, assembled from steel wires, formed from powder, or 3D - printed. Simulations based on the WB3D code demonstrate that using such undulators with the length of (30-40) cm enable single-mode super-radiance from bunches with energy of 6 MeV, charge of 1 nC and duration of 2 ps moving in an over-sized waveguide in frequency range of 3-5 THz. The calculated efficiency of such process is (2-4)% that many times exceeds efficiency for short bunches of the same initial density. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP086 | |
| About • | paper received ※ 14 August 2019 paper accepted ※ 28 August 2019 issue date ※ 05 November 2019 | |
| Export • | reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |
| THP024 | Spontaneous Coherent Radiation of Stabilized Dense Electron Bunches | 643 |
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Funding: The work is supported by Russian Foundation for Basic Research Project 18-32-00351, 18-02-00765 Modern sources of dense electron beams allow the formation of compact sources of dense electron bunches with energies of 3-6 MeV, ps pulse durations, and charges of up to 1 nC. Such bunches can be used for the realization of relatively simple and compact powerful terahertz sources based on spontaneous coherent radiation. The power and duration of the process of such type of emission are limited due to an increase in the bunch length under the Coulomb repulsion. This complicates the effective implementation of the regime of spontaneous coherent radiation for dense bunches. Therefore, special methods for stabilization of the length of the operating e-bunch during its motion over a long electron-wave interaction region should be used. We propose several methods of the stabilization based on the axial bunch compression by self-radiated wave fields [1] and by quasi-static Coulomb fields inside a bunch [2]. The latter takes place in the case of the motion of electrons through the undulator in the "negative-mass" regime, when the Coulomb field inside the bunch leads not to repulsion of electrons but to their mutual attraction. [1] I. V. Bandurkin, Yu. S. Oparina and A. V. Savilov, Appl. Phys. Lett. vol 110, p. 263508, 2017 [2] N. Balal, I. V. Bandurkin, V. L. Bratman, E. Magory, and A. V. Savilov, Appl. Phys. Lett. vol. 107, p. 163505, 2015 |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP024 | |
| About • | paper received ※ 19 August 2019 paper accepted ※ 12 September 2019 issue date ※ 05 November 2019 | |
| Export • | reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |