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12 pages, 4657 KiB

Open AccessArticle

Investigation of High-Q Lithium Niobate-Based Double Ring Resonator Used in RF Signal Modulation

by Zhenlin Wu, Lin Zhang, Shaoshuai Han, Di Lian, Tongfei Wu, Wenjie Chu, Haoyu Li, Lei Guo, Mingshan Zhao and Xin Yang

Appl. Sci. 2023, 13(7), 4648; https://doi.org/10.3390/app13074648 - 6 Apr 2023

Viewed by 2248

Abstract

In recent years, millimeter-wave communication has played a crucial role in satellite communication, 5G, and even 6G applications. The millimeter-wave electro-optic modulator is capable of receiving and processing millimeter-wave signals effectively. However, the large attenuation of millimeter waves in the air remains a [...] Read more.

In recent years, millimeter-wave communication has played a crucial role in satellite communication, 5G, and even 6G applications. The millimeter-wave electro-optic modulator is capable of receiving and processing millimeter-wave signals effectively. However, the large attenuation of millimeter waves in the air remains a primary limiting factor for their future applications. Therefore, finding a waveguide structure with a high quality factor (Q-factor) is critical for millimeter-wave electro-optic modulators. This manuscript presents the demonstration of a double ring modulator made of lithium niobate with the specific goal of modulating an RF signal at approximately 35 GHz. By optimizing the microring structure, the double ring resonator with high Q-factor is studied to obtain high sensitivity modulation of the RF signal. This manuscript employs the transfer matrix method to investigate the operational principles of the double ring structure and conducts simulations to explore the influence of structural parameters on its performance. Through a comparison with the traditional single ring structure, it is observed that the Q-factor of the double ring modulator can reach 7.05 × 10⁸, which is two orders of magnitude greater than that of the single ring structure. Meanwhile, the electro-optical tunability of the double ring modulator is 6 pm/V with a bandwidth of 2.4 pm, which only needs 0.4 V driving voltage. The high Q double ring structure proposed in this study has potential applications not only in the field of communication but also as a promising candidate for a variety of chemical and biomedical sensing applications. Full article

(This article belongs to the Special Issue RF-Based Undulators and High-Gradient Accelerator Fed by High-Frequency Electromagnetic Devices)

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24 pages, 1393 KiB

Open AccessArticle

A Collection of Formulae for the Design of Compton Back-Scattering X-ray Sources

by Giuseppe Dattoli, Emanuele Di Palma and Vittoria Petrillo

Appl. Sci. 2023, 13(4), 2645; https://doi.org/10.3390/app13042645 - 18 Feb 2023

Cited by 2 | Viewed by 1615

Abstract

Along with the development of FEL X-ray sources, the design and the construction of Compton Back-Scattering (CBS) devices for different applications are being pursued. These sources are designed to provide monochromatic, high peak brightness tunable light beams, with photon energies above 10 [...] Read more.

Along with the development of FEL X-ray sources, the design and the construction of Compton Back-Scattering (CBS) devices for different applications are being pursued. These sources are designed to provide monochromatic, high peak brightness tunable light beams, with photon energies above 10

K e V

. The source brightness is the most significant figure of merit, which specifies the suitability of X-ray beams for their application in a specific field of interest and also reflects the quality of the electron beam itself, which in turn depends on the charge, emittance, energy spread, etcetera. This article is intended as an introductory review to the field and we embed a few theoretical considerations and analytical formulae to develop simple tools for the design of CBS X-ray sources. The present attempt is analogous to previous efforts, put forward to model Free Electron Laser devices, using scaling relations accounting for the entanglement between the different physical quantities contributing to the output beam performances. We comment on the reliability of our analysis by a comparison with the wealth of results (either numerical and analytical) reported in the dedicated literature. Full article

(This article belongs to the Special Issue RF-Based Undulators and High-Gradient Accelerator Fed by High-Frequency Electromagnetic Devices)

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16 pages, 2814 KiB

Open AccessArticle

State of the Art of High-Flux Compton/Thomson X-rays Sources

by Vittoria Petrillo, Illya Drebot, Marcel Ruijter, Sanae Samsam, Alberto Bacci, Camilla Curatolo, Michele Opromolla, Marcello Rossetti Conti, Andrea Renato Rossi and Luca Serafini

Appl. Sci. 2023, 13(2), 752; https://doi.org/10.3390/app13020752 - 5 Jan 2023

Cited by 15 | Viewed by 2975

Abstract

In this paper, we present the generalities of the Compton interaction process; we analyse the different paradigms of Inverse Compton Sources, implemented or in commissioning phase at various facilities, or proposed as future projects. We present an overview of the state of the [...] Read more.

In this paper, we present the generalities of the Compton interaction process; we analyse the different paradigms of Inverse Compton Sources, implemented or in commissioning phase at various facilities, or proposed as future projects. We present an overview of the state of the art, with a discussion of the most demanding challenges. Full article

(This article belongs to the Special Issue RF-Based Undulators and High-Gradient Accelerator Fed by High-Frequency Electromagnetic Devices)

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12 pages, 981 KiB

Open AccessArticle

Performance Study on a Soft X-ray Betatron Radiation Source Realized in the Self-Injection Regime of Laser-Plasma Wakefield Acceleration

by Alessandro Curcio, Alessandro Cianchi, Gemma Costa, Francesco Demurtas, Michael Ehret, Massimo Ferrario, Mario Galletti, Danilo Giulietti, José Antonio Pérez-Hernández and Giancarlo Gatti

Appl. Sci. 2022, 12(23), 12471; https://doi.org/10.3390/app122312471 - 6 Dec 2022

Cited by 3 | Viewed by 1746

Abstract

We present an analysis of the performance of a broadband secondary radiation source based on a high-gradient laser-plasma wakefield electron accelerator. In more detail, we report studies of compact and ultra-short X-ray generation via betatron oscillations in plasma channels. For the specific working [...] Read more.

We present an analysis of the performance of a broadband secondary radiation source based on a high-gradient laser-plasma wakefield electron accelerator. In more detail, we report studies of compact and ultra-short X-ray generation via betatron oscillations in plasma channels. For the specific working point examined in this paper, determined by the needs of other experiments ongoing at the facility, at ∼0.02 Hz operation rate, we have found ≲

10^{6}

photons emitted per shot (with a fluctuation of

50 %

) in the soft X-rays, corresponding to a critical energy of ∼0.8 keV (with a fluctuation of 40%). The source will be implemented for experiments in time-domain spectroscopy, e.g., biological specimens, and for other applications oriented to medical physics. Full article

(This article belongs to the Special Issue RF-Based Undulators and High-Gradient Accelerator Fed by High-Frequency Electromagnetic Devices)

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24 pages, 1281 KiB

Open AccessArticle

Comments on the Physics of Microwave-Undulators

by Emanuele Di Palma, Giuseppe Dattoli and Svilen Sabchevski

Appl. Sci. 2022, 12(20), 10297; https://doi.org/10.3390/app122010297 - 13 Oct 2022

Cited by 2 | Viewed by 1395

Abstract

The properties of electromagnetic undulators, produced by the field of a high-power microwave, are discussed. We analyze the conditions to be satisfied that allow the treatment of the emission process by relativistic charges moving through it in full analogy with the case of [...] Read more.

The properties of electromagnetic undulators, produced by the field of a high-power microwave, are discussed. We analyze the conditions to be satisfied that allow the treatment of the emission process by relativistic charges moving through it in full analogy with the case of their static counterparts. We critically review the often claimed possibility of exploiting them in programs aimed at reducing the sizes and costs of an actual free electron laser (FEL) device. We analyze several possible configurations for FELs based on powerful microwave undulators and conclude that the present level of technology, even though not yet mature, should be improved to allow a breakthrough either for low- or high-gain devices. Full article

(This article belongs to the Special Issue RF-Based Undulators and High-Gradient Accelerator Fed by High-Frequency Electromagnetic Devices)

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15 pages, 1384 KiB

Open AccessArticle

Synchronised TeraHertz Radiation and Soft X-rays Produced in a FEL Oscillator

by Vittoria Petrillo, Alberto Bacci, Illya Drebot, Michele Opromolla, Andrea Renato Rossi, Marcello Rossetti Conti, Marcel Ruijter, Sanae Samsam and Luca Serafini

Appl. Sci. 2022, 12(16), 8341; https://doi.org/10.3390/app12168341 - 20 Aug 2022

Cited by 3 | Viewed by 1617

Abstract

We present a scheme to generate synchronised THz and soft X-ray radiation pulses by using a free-electron laser oscillator driven by a high repetition rate (of order 10–100 MHz) energy recovery linac. The backward THz radiation in the oscillator cavity interacts with a [...] Read more.

We present a scheme to generate synchronised THz and soft X-ray radiation pulses by using a free-electron laser oscillator driven by a high repetition rate (of order 10–100 MHz) energy recovery linac. The backward THz radiation in the oscillator cavity interacts with a successive electron bunch, thus producing few

10^{5}

soft/hard X-ray photons per shot (namely

10^{12}

–

10^{13}

photons/s) via Thomson/Compton back-scattering, synchronised with the mJ-class THz pulse within the temporal jitter of electron beams accelerated in the superconducting cavities of the linac (less than 100 fs). Detailed simulations have been performed in order to assess the capability of the scheme for typical wavelengths of interest, between 10 and 50

μ

m for the TeraHertz radiation and 0.5–3 nm for the X-rays. Full article

(This article belongs to the Special Issue RF-Based Undulators and High-Gradient Accelerator Fed by High-Frequency Electromagnetic Devices)

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Review

Jump to: Research

19 pages, 2438 KiB

Open AccessReview

Design Criteria for High-Gradient Radio-Frequency Linacs

by Valery A. Dolgashev

Appl. Sci. 2023, 13(19), 10849; https://doi.org/10.3390/app131910849 - 29 Sep 2023

Cited by 4 | Viewed by 1482

Abstract

This article will review methods used at the SLAC National Accelerator Laboratory and other world accelerator laboratories to design high-gradient normal conducting accelerating structures. A quest for compact radio-frequency linacs fueled decades of studies toward a higher accelerating gradient. A major phenomena limiting [...] Read more.

This article will review methods used at the SLAC National Accelerator Laboratory and other world accelerator laboratories to design high-gradient normal conducting accelerating structures. A quest for compact radio-frequency linacs fueled decades of studies toward a higher accelerating gradient. A major phenomena limiting the increase of the gradient is vacuum radio-frequency breakdown; therefore, this paper will address the breakdown physics and discuss approaches that reduce the breakdown probability. This discussion will cover both the electrical design and fabrication technology of the accelerating structures to achieve practical operating accelerating gradients in excess of 100 MV/m. Most of the data described here were obtained during the development of 11 GHz linacs for electron–positron linear colliders, so extrapolation of the results to other frequencies should be performed cautiously. Full article

(This article belongs to the Special Issue RF-Based Undulators and High-Gradient Accelerator Fed by High-Frequency Electromagnetic Devices)

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14 pages, 2546 KiB

Open AccessReview

Gyrotrons as High-Frequency Drivers for Undulators and High-Gradient Accelerators

by Svilen Sabchevski, Emanuele Di Palma, Ivan Spassovsky and Giuseppe Dattoli

Appl. Sci. 2022, 12(12), 6101; https://doi.org/10.3390/app12126101 - 15 Jun 2022

Viewed by 2440

Abstract

Gyrotrons are used as high-power sources of coherent radiation operating in pulsed and CW regimes in many scientific and technological fields. In this paper, we discuss two of their numerous applications. The first one is in gyrotron-powered electromagnetic wigglers and undulators. The second [...] Read more.

Gyrotrons are used as high-power sources of coherent radiation operating in pulsed and CW regimes in many scientific and technological fields. In this paper, we discuss two of their numerous applications. The first one is in gyrotron-powered electromagnetic wigglers and undulators. The second one is for driving high-gradient accelerating structures in compact particle accelerators. The comparison, between the requirements imposed by these two concepts on the radiation sources on one hand and the output parameters of the currently available high-performance gyrotrons on the other hand, show that they match each other to a high degree. We consider this as a manifestation of the feasibility and potential of these concepts. It is believed that after the first successful proof-of-principle experiments they will find more wide usage in the advanced FEL and particle accelerators. Full article

(This article belongs to the Special Issue RF-Based Undulators and High-Gradient Accelerator Fed by High-Frequency Electromagnetic Devices)

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