Electron bunchers for industrial RF linear accelerators: theory and design guide

Kutsaev, Sergey

doi:10.1140/epjp/s13360-021-01312-3

Cited by 20 publications

(11 citation statements)

References 77 publications

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“…A conceptual design for the typical high-current linac is presented in Figure 2. While this design differs from those of standard medical linacs, the design is characteristic of those found in high-current industrial settings and scientific laboratories (Adolphsen et al, 2014;Kutsaev, 2021a) The thermionic electron gun with a DC Pierce geometry gun and gridded cathode can provide 1.5-3 A continuous beam, accelerated to 100-150 keV energies, so that losses in the injection system yield at least 25% of the initial current after the acceleration.…”

Section: Accelerator Designmentioning

confidence: 99%

Feasibility study of high-power electron linac for clinical X-ray ROAD-FLASH therapy system

Kutsaev,

Agustsson,

Boucher

et al. 2024

Front. Med. Eng.

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Introduction: This study examines how a practical source of X-ray radiation, capable of delivering unprecedented X-ray of 100 Gy/s at 1 m for X-ray FLASH radiotherapy can be designed.Methods: We proposed the design of a linac, capable of accelerating 18 MeV 8 mA electron beam with further conversion to bremsstrahlung X-rays. The design is based on L-band traveling wave accelerating structures with high power efficiency, operating in a short-burst/long-pulse regime that allows operating power supply in a regime, beyond its specifications.Results: This study demonstrates the feasibility of a high-power linac for a clinical X-ray FLASH therapy system, using detailed analysis and simulations. Despite ∼500x higher output than a standard clinical linac, the design utilizes available accelerator components for maximal practicality.Discussion: Recent studies have demonstrated that the FLASH effect that allows to effectively kill tumor cells while sparing normal tissue occurs when large dose rates (≥40 Gy/s) are delivered in less than 1 s. Photons are very attractive since modest energies of several MeV are needed, which can be achieved with compact and cost-efficient accelerators. However, since the efficiency of electron-to-photon conversion is only a few percent, the required beam intensity must be an order of magnitude higher than that state-of-the-art accelerators can provide. The proposed ROAD-FLASH accelerator layout allows achieving both the FLASH dose rate and superior dose conformity, comparing to the similar projects. The current paper focuses on providing a technical roadmap for building an economical and practical linear accelerator for ROAD X-ray FLASH delivery.

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Section: Accelerator Designmentioning

confidence: 99%

Feasibility study of high-power electron linac for clinical X-ray ROAD-FLASH therapy system

Kutsaev,

Agustsson,

Boucher

et al. 2024

Front. Med. Eng.

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“…In this section, we have summarized the techniques used to simulate the geometry of a medical linear accelerator by two codes based on the Geant4 toolkit: G4Linac_MT [8] and GATE [14]. The efficiency of the Monte Carlo calculation depends on the simulated events, the correct initiation of the initial parameters, the correct modeling of the LINAC geometry.…”

Section: Monte Carlo Simulationmentioning

confidence: 99%

“…accelerated to create collisions on the target. The energy of the electrons accelerated by the 6MV voltage is generally between 0 and 9 MeV [8,25]. In the Monte Carlo simulation of the dose delivered by LINACs, only the treatment head is modeled from the x-ray target.…”

Section: Initial Parametersmentioning

confidence: 99%

“…For this purpose, we have simulated three types of photon beams (x-rays) 6 MV in filtered and unfiltered mode and the high energy 18 MV. The operating principle of a photon mode medical accelerator is to create a collision between accelerated electrons and a thin and very dense target [8][9][10]. The accelerated electrons are considered in first approach as having a Gaussian distribution [11,12].…”

Section: Introductionmentioning

confidence: 99%

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Effect of the Gaussian distribution parameters of the electron beam generated at the target on the simulated x-ray dose

Assalmi¹,

Diaf²

2023

Biomed. Phys. Eng. Express

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The purpose of this work was to investigate by Monte Carlo method the adjustment of photon beams delivered by the medical LINear ACcelerator (LINAC) Elekta Synergy MLCi2. This study presents an optimization of the Gaussian distribution parameters of the accelerated electrons before the target simulated by two Monte Carlo codes and for three beams. The photon (X-ray) beam is produced by the interaction of accelerated electrons with the LINAC target. The electrons are accelerated by a potential difference created between the anode and the cathode of the gun and directed towards the target. In the Monte Carlo simulation, it is necessary to setup the spectrum parameters of the generated electrons to simulate the X-ray dose distribution. In this study, we modeled the LINAC geometry for photon beams 18MV and 6MV in cases Flattened (FF) and Flattening-Filter-Free (FFF). The Monte Carlo simulations are based on G4Linac_MT and GATE codes. The results of the optimized configurations determined after more than 20 tests for each beam energy show a very good agreement with the experimental measurements for different irradiation fields for the depth (PDD) and lateral (Profile) dose distribution. In all Monte Carlo calculations performed in this study, the statistical uncertainty is less than 2%. The results were also in very good agreement in terms of γ-index analysis, for the 3%/3mm and 2%/2mm criteria.

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“…The split structure has higher efficiency (shunt impedance and Q-factor) due to the thinner iris, and also higher peak electric and magnetic fields for the same gradient due to the gap between halves. It is worth noting that some parameters (peak-to-accelerating-field ratio, filling time and pulse heating) are higher than they will be in a traveling wave structure of the same iris shape [34].…”

Section: Design and Simulationsmentioning

confidence: 99%

Experimental studies of a high-gradient X-band welded hard-copper split accelerating structure

Agustsson¹,

Carriere²,

Chimalpopoca³

et al. 2022

J. Phys. D: Appl. Phys.

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Recent research on high-gradient radio frequency (RF) accelerating structures indicates that the use of hard copper alloys provides improvement in high gradient performance over annealed copper. Such structures are made by bonding individually manufactured parts. However, there are no well-established bonding techniques that preserve the hardness, surface finish and cleanliness required for high gradient operation. To preserve the copper hardness, RadiaBeam has developed a joining technique based on electron beam welding. This technique provides efficient bonding with strong, clean welds and minimal thermal loading, while maintaining a clean inner RF environment. Our RF design and fabrication methodology limits the small heat affected zone to the outer cavity envelop, with virtually no distortions or thermal loading of critical RF surfaces. It also incorporates provisions to precisely control the gap despite conventional issues with weld joint shrinkage. To date we have manufactured and validated an RF accelerating structure joined by electron-beam welding that incorporates a novel open split design to significantly reduce the assembly complexity and cost. In this paper, we will present the electromagnetic design of this structure, discuss bonding, and present the results of high-power tests, where the accelerating gradients of 140 MV/m with surface peak fields of 400 MV/m were achieved for flat-top pulse length of 600 ns with an RF breakdown rate of 10-4 1/(pulse∙m).

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Electron bunchers for industrial RF linear accelerators: theory and design guide

Cited by 20 publications

References 77 publications

Feasibility study of high-power electron linac for clinical X-ray ROAD-FLASH therapy system

Feasibility study of high-power electron linac for clinical X-ray ROAD-FLASH therapy system

Effect of the Gaussian distribution parameters of the electron beam generated at the target on the simulated x-ray dose

Experimental studies of a high-gradient X-band welded hard-copper split accelerating structure

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