Daniel González-Iglesias

Instituto de Física Corpuscular

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Co-Authors

B. Gimeno

Universitat de València

D. Esperante Pereira

Universitat de València

Pablo Martín-Luna

Instituto de Física Corpuscular

Vicente E. Boria

Universitat Politècnica de València

Nuria Fuster-Martínez

Instituto de Física Corpuscular

Pablo Martinez-Reviriego

Instituto de Física Corpuscular

J. Fuster

Instituto de Física Corpuscular

David Raboso

European Space Research and Technology Centre

C. Blanch

Instituto de Física Corpuscular

S. Anza

Dassault Systèmes (France)

Cooperative Institutions

European Organization for Nuclear Research

Universitat de València

Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati

Cockcroft Institute

Instituto de Física Corpuscular

Istituto Nazionale di Fisica Nucleare

Sci-Tech Daresbury

Universitat Politècnica de València

Sapienza University of Rome

Centre National de la Recherche Scientifique

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Corrections to “Multipactor Susceptibility Charts for Ridge and Multi-Ridge Waveguides” [Dec 12 3601-3607]

IEEE Transactions on Electron Devices (2013)

Daniel González-Iglesias Pablo Soto S. Anza B. Gimeno Vicente E. Boria

The authors have detected an error in Section IV-A in the above paper (ibid., vol. 59, no. 12, pp. 3601-3607, Dec. 2012). The analyzed rectangular waveguide in the actual version of the article is the WR137, instead of the WR90. As a consequence, the corrections presented here have to be implemented.

Section (typography)

10.1109/ted.2013.2288795

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Citations (1)

Enhancement of the Multipactor Threshold Inside Nonrectangular Iris

IEEE Transactions on Electron Devices (2018)

V. E. Semenov E. Rakova Edén Sorolla Daniel González-Iglesias O. Monerris

Multipactor breakdown is studied inside the capacitive iris of a rectangular waveguide with a skewed slot along its longitudinal cross section. Both the iris length and height are assumed to be small compared to the electromagnetic wavelength. Therefore, the quasi-static approximation is applied so as to describe the RF field distribution inside the iris gap, whereas a 2-D model is used to analyze the electron motion. The peculiarities of RF field structure are studied using the conformal mapping approach, which shows that the electric field lines can be approximated by circular arcs when the iris length is much larger than its height. The electron motion inside the iris gap is analyzed using different analytical approaches as well as numerical simulations. The simplest analytical consideration is based on the general theory of multipactor between curved surfaces. Within the more sophisticated model, the fringing field effect on electron motion inside the iris is calculated assuming circular structure of electric field lines. It is demonstrated within all approaches that the electron losses within the iris gap increase considerably with the skew angle, deviating from the rectangular iris shape. As a result, the multipactor becomes impossible at a relatively small value of this angle.

IRIS (biosensor)

10.1109/ted.2018.2798538

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Citations (4)

Experimental Analysis of the Multipactor Effect With RF Pulsed Signals

IEEE Electron Device Letters (2015)

Daniel González-Iglesias Oscar Monerris Belda María Elena Díaz B. Gimeno Vicente E. Boria

The main goal of this letter is the analysis of the multipactor effect within a coaxial waveguide excited by an RF pulsed signal. The variation of the multipactor RF voltage threshold with the ON interval length of the pulse has been analyzed. To reach this aim, an in-house multipactor simulation code based on the Monte-Carlo algorithm has been implemented. The numerical simulations show that the multipactor RF voltage threshold increases as the ON pulse interval diminishes. In addition, an experiment was carried out to validate the proposed theoretical model, and demonstrating the excellent agreement between the theory and the experimental data. Finally, the results are compared with the 20-gap-crossing rule used in the space standard document (ECSS-E20-1A).

Coaxial

SIGNAL (programming language)

10.1109/led.2015.2468068

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Citations (11)

Analytical RF Pulse Heating Analysis for High Gradient Accelerating Structures

IEEE Transactions on Nuclear Science (2021)

Daniel González-Iglesias D. Esperante Pereira B. Gimeno M. Boronat C. Blanch

The main aim of this work is to present a simple method, based on analytical expressions, for obtaining the temperature increase due to the Joule effect inside the metallic walls of an RF accelerating component.This technique relies on solving the 1D heat transfer equation for a thick wall, considering that the heat sources inside the wall are the ohmic losses produced by the RF electromagnetic fields penetrating into the metal with finite electrical conductivity.Furthermore, it is discussed how the theoretical expressions of this method can be applied to obtain an approximation to the temperature increase in realistic 3D RF accelerating structures, taking as an example the cavity of an RF electron photoinjector and a travelling wave linac cavity.These theoretical results have been benchmarked with numerical simulations carried out with a commercial Finite Element Method (FEM) software, finding good agreement among them.Besides, the advantage of the analytical method with respect to the numerical simulations is evidenced.In particular, the model could be very useful during the design and optimization phase of RF accelerating structures, where many different combinations of parameters must be analysed in order to obtain the proper working point of the device, allowing to save time and speed up the process.However, it must be mentioned that the method described in this manuscript is intended to provide a quick approximation to the temperature increase in the device, which of course is not as accurate as the proper 3D numerical simulations of the component.

Joule effect

Cavity wall

10.1109/tns.2021.3049319

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Citations (3)

Non-resonant ultra-fast multipactor regime in dielectric-assist accelerating structures

Results in Physics (2023)

Daniel González-Iglesias B. Gimeno D. Esperante Pereira Pablo Martinez-Reviriego Pablo Martín-Luna

The objective of this work is the evaluation of the risk of suffering a multipactor discharge in an S-band dielectric-assist accelerating (DAA) structure for a compact low-energy linear particle accelerator dedicated to hadrontherapy treatments. A DAA structure consists of ultra-low loss dielectric cylinders and disks with irises which are periodically arranged in a metallic enclosure, with the advantage of having an extremely high quality factor and very high shunt impedance at room temperature, and it is therefore proposed as a potential alternative to conventional disk-loaded copper structures. However, it has been observed that these structures suffer from multipactor discharges. In fact, multipactor is one of the main problems of these devices, as it limits the maximum accelerating gradient. Because of this, the analysis of multipactor risk in the early design steps of DAA cavities is crucial to ensure the correct performance of the device after fabrication. In this paper, we present a comprehensive and detailed study of multipactor in our DAA design through numerical simulations performed with an in-house developed code based on the Monte–Carlo method. The phenomenology of the multipactor (resonant electron trajectories, electron flight time between impacts, etc.) is described in detail for different values of the accelerating gradient. It has been found that in these structures an ultra-fast non-resonant multipactor appears, which is different from the types of multipactor theoretically studied in the scientific literature. In addition, the effect of several low electron emission coatings on the multipactor threshold is investigated. Furthermore, a novel design based on the modification of the DAA cell geometry for multipactor mitigation is introduced, which shows a significant increase in the accelerating gradient handling capabilities of our prototype.

Secondary electrons

Secondary emission

10.1016/j.rinp.2023.107245

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Citations (1)

Multipactor Rf breakdown analysis in a parallel-plate waveguide partially filled with a magnetized ferrite slab

Daniel González-Iglesias Álvaro Gómez Gómez B. Gimeno Α. Vegas F. J. Casas

Oral presentation given at the 9th International Workshop on Microwave Discharges: Fundamentals and Applications, held on September 7-11th, 2015, in Cordoba (Spain).

Slab

Waveguide

Source

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On the magnetostatic scalar potential and magnetic field of a cylindrical magnet

European Journal of Physics (2024)

Pablo Martín-Luna Benito Gimeno Martínez Daniel González-Iglesias M. Boronat Nuria Fuster-Martínez

Abstract The magnetostatic potential and magnetic field of a solid and hollow cylindrical magnet is calculated everywhere in space in terms of complete elliptic integrals. These expressions are calculated using an electromagnetic analogy with the electrostatic potential and electric field of two uniformly charged disks with opposite surface density. The analogy is employed to study intuitively the discontinuities and the dipolar approximation of the fields H ⃗ and B ⃗ . The range of validity of the dipolar approximation has been studied along the cylinder axis and in the midplane perpendicular to the cylinder axis, comparing them with the obtained general expression.

Scalar potential

10.1088/1361-6404/ad7f30

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Dielectric Assist Accelerating Structures for Compact Linear Accelerators of Low Energy Particles in Hadrontherapy Treatments

arXiv (Cornell University) (2023)

Pablo Martinez-Reviriego D. Esperante Pereira Alexej Grudiev B. Gimeno C. Blanch

Dielectric Assist Accelerating (DAA) structures based on ultralow-loss ceramic are being studied as an alternative to conventional disk-loaded copper cavities. This accelerating structure consists of dielectric disks with irises arranged periodically in metallic structures working under the TM$_{02}$-$\pi$ mode. In this paper, the numerical design of an S-band DAA structure for low beta particles, such as protons or carbon ions used for Hadrontherapy treatments, is shown. Four dielectric materials with different permittivity and loss tangent are studied as well as different particle velocities. Through optimization, a design that concentrates most of the RF power in the vacuum space near the beam axis is obtained, leading to a significant reduction of power loss on the metallic walls. This allows to fabricate cavities with an extremely high quality factor, over 100 000, and shunt impedance over 300 M$\Omega$/m at room temperature. During the numerical study, the design optimization has been improved by adjusting some of the cell parameters in order to both increase the shunt impedance and reduce the peak electric field in certain locations of the cavity, which can lead to instabilities in its normal functioning.

Dielectric loss

Dissipation factor

10.48550/arxiv.2308.03674

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CompactLight design study

HAL (Le Centre pour la Communication Scientifique Directe) (2019)

G. D’Auria Markus Aicheler Avni Aksoy David Alesini R. Apsimon

The H₂020 CompactLight Project (www. CompactLight.eu) aims at designing the next generation of compact X-rays Free-Electron Lasers, relying on very high gradient accelerating structures (X-band, 12 GHz), the most advanced concepts for bright electron photo injectors, and innovative compact short-period undulators. Compared to existing facilities, the proposed facility will benefit from a lower electron beam energy, due to the enhanced undulators performance, and will be significantly more compact, with a smaller footprint, as a consequence of the lower energy and the high-gradient X-band structures. In addition, the whole infrastructure will also have a lower electrical power demand as well as lower construction and running costs.

Footprint

10.18429/jacow-ipac2019-tuprb032

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Citations (8)

Multipactor Susceptibility Charts for Ridge and Multiridge Waveguides

IEEE Transactions on Electron Devices (2012)

Daniel González-Iglesias Pablo Soto S. Anza B. Gimeno Vicente E. Boria

The aim of this letter is to study the multipactor RF breakdown voltage in several ridge and multi-ridge waveguide configurations.Firstly, multipactor susceptibility charts for several types of ridged waveguides have been computed using the commercial software FEST3D.Next, these charts have been used to predict multipactor threshold values for a band-pass filter and a quasi low-pass filter both containing ridge waveguide sections.Furthermore, multipactor simulations using FEST3D are carried out to calculate the multipactor threshold of the aforementioned structures.A good agreement between predictions and simulations has been found for both filter examples.

Waveguide

Waveguide filter

10.1109/ted.2012.2215611

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Citations (14)