A SW Ka-Band linearizer structure with minimum surface electric field for the compact light XLS project

Behtouei, Mostafa; Faillace, L.; Spataro, B.; Variola, A.; Migliorati, M.

doi:10.1016/j.nima.2020.164653

Cited by 11 publications

(12 citation statements)

References 15 publications

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“…By choosing a length of 16 cm and an iris radius of 1 mm, we then provide the evaluation for the best performing type of accelerating scheme, for both standing-wave (SW) or travelingwave (TW) cases. As published in [39], we demonstrated that the optimal maximum length for the SW structure is around 8 cm, in order to avoid resonant mode overlapping. In SW operation, our proposal is then to utilize two SW structures, each 8 cm long, fed by a 3dB hybrid coupler.…”

Section: Motivationmentioning

confidence: 74%

“…This component is critically important for applications such as the MaRIE XFEL [38], the CompactLight FEL, the Ultra-Compact XFEL at UCLA [9]. Paired with the CompactLight sponsored initiative to develop a 15 MW-class klystron at 36 GHz, a compact, high gradient cryogenic linearizer in this frequency range now seems within reach [39].…”

Section: Cryogenic Operation Of a Ka-band Rf Linearizermentioning

confidence: 99%

“…Exhaustive discussions on the design cavity criteria in order to choose the cavity RF parameters have already described elsewhere [39,40,41] in case of Ka-band structure to be used for the Compact Light XLS project.…”

Section: Cavity Choice Criteriamentioning

confidence: 99%

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Ultra-Compact Ka-band linearizer for the Ultra-Compact X-Ray Free-Electron Laser at UCLA

Spataro,

Behtouei,

Faillace

et al. 2021

Preprint

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There is a strong demand for accelerating structures able to achieve higher gradients and more compact dimensions for the next generation of linear accelerators for research, industrial and medical applications.Notably innovative technologies will permit compact and affordable advanced accelerators as the linear collider and X-ray freeelectron lasers (XFELs) with accelerating gradients over twice the value achieved with current technologies. In particular XFEL is able to produce coherent X-ray pulses with peak brightness 10 orders of magnitude greater than preceding approaches, which has revolutionized numerous fields through imaging of the nanoscopic world at the time and length scale of atom-based systems, that is of femtosecond and Angstrom. There is a strong interest for combining these two fields, to form a proper tool with the goal of producing a very compact XFEL in order to investigate multi-disciplinary researches in chemistry, biology, materials science, medicine and physics.In the framework of the Ultra -Compact XFEL project (UC-XFEL) under study at the University of California of Los Angeles (UCLA), an ultra high gradient higher harmonic radio-frequency (RF) accelerating structure for the longitudinal space phase linearization is foreseen. To this aim, a Ka-Band linearizer (34.2 GHz) with an integrated voltage of at least 15 MV working on 6th harmonic with respect to the main Linac frequency (5.712 GHz) is required. We here present the electromagnetic design of a cold ultra compact Ka-band standing wave (SW) linearizer, 8 cm long, working on π mode with an ultra high accelerating gradient (beyond 100 MV/m) and minimum surface electric field for minimizing the probability of RF breakdown. Moreover, we discuss a traveling-wave (TW) option and compare it with the initial SW structure, by means of main RF parameters as well as beamdynamics considerations. The numerical electromagnetic studies have been performed by using the well known SuperFish, HFSS and CST computing software.

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Section: Motivationmentioning

confidence: 74%

Section: Cryogenic Operation Of a Ka-band Rf Linearizermentioning

confidence: 99%

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Ultra-Compact Ka-band linearizer for the Ultra-Compact X-Ray Free-Electron Laser at UCLA

Spataro,

Behtouei,

Faillace

et al. 2021

Preprint

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“…In order to linearize the longitudinal space phase of the Compact Light XLS project a Ka-Band accelerating structure operating on the mode at the third RF harmonic with respect to the main linac RF frequency has been considered [27][28][29]. The linearizer can work with a high accelerating gradient around up to 150 MV/m [30].…”

Section: Discussionmentioning

confidence: 99%

The Ka-band high power klystron amplifier design program of INFN

Behtouei

Spataro

Paolo

et al. 2021

Vacuum

Self Cite

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In the framework of the Compact Light XLS project, a short ultra-high gradient linearizer working on the third harmonic of the main linac frequency is requested. Increasing gradients and reducing dimensions are requirements for XLS and all next generation linear accelerators. Actually, ultra-compact normal conducting accelerating structures, operating in the Ka-band are required to achieve ultra-high gradients for research, industrial and medical applications, with electric field ranging from 100 to 150 MV/m. To fulfill these strong requirements, the R&D of a proper Ka-band klystron with high RF power output and a high efficiency is mandatory. This contribution reports the design of a possible klystron amplifier tube operating on the 010 mode at 36 GHz, the third harmonic of the 12 GHz linac frequency, with an efficiency of 42% and a 20 MW RF power output. This contribution discusses also the high-power DC gun, the beam focusing channel and the RF beam dynamics.

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“…In the framework of the "Compact Light XLS" project [1], a short ultra-high gradient linearizer working on the third harmonic (∼36 GHz) of the bunched electron beam and generated by a high-voltage DC gun (up to 480 kV) operating with an accelerating gradient of ∼150 MV/m (i.e., 15-20 MV integrated voltage range) is requested [2,3,4,5] . To meet these requirements, a 36 GHz pulsed Ka-band RF power source with a pulse length of 100 ns and a repetition frequency in the (1-10) Hz range with an output power of (50-60) MW is necessary [6,7,8].…”

Section: Introductionmentioning

confidence: 99%

Relativistic approach to a low perveance high quality matched beam for a high efficiency Ka-Band klystron

Behtouei,

Spataro,

Faillace

et al. 2021

Preprint

Self Cite

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Advanced technical solution for the design of a low perveance electron gun with a high quality beam dedicated to high power Ka-band klystrons is presented in this paper. The proposed electron gun can be used to feed linear accelerating structures at 36 GHz with an estimated input power of 20 MW, thus achieving an effective accelerating electric field in the (100-150) MV/m range. additionally, in the framework of the Compact Light XLS project, a short Ka-band accelerating structure providing an integrated voltage of at least 15 MV, has been proposed for bunch-phase linearization. For the klystron, a very small beam dimension is needed and the presented electron gun responds to this requirement. An estimate of the rotational velocity at beam edge indicates that the diamagnetic field due to rotational currents are small compared to the longitudinal volume. A detailed analysis of how this is arrived at, by compression of the beam, rotation in the magnetic field, and analysis of the subsequently generated diamagnetic field has been discussed.

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A SW Ka-Band linearizer structure with minimum surface electric field for the compact light XLS project

Cited by 11 publications

References 15 publications

Ultra-Compact Ka-band linearizer for the Ultra-Compact X-Ray Free-Electron Laser at UCLA

Ultra-Compact Ka-band linearizer for the Ultra-Compact X-Ray Free-Electron Laser at UCLA

The Ka-band high power klystron amplifier design program of INFN

Relativistic approach to a low perveance high quality matched beam for a high efficiency Ka-Band klystron

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