Development of an automatic frequency control system for an X-band (=9300 MHz) RF electron linear accelerator

Cha, Sungsu; Kim, Yujong; Lee, Byung Cheol; Park, Hyung Dal; Lee, Seung Hyun; Buaphad, Pikad

doi:10.1016/j.nima.2017.03.005

Cited by 4 publications

(2 citation statements)

References 8 publications

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“…Therefore, in order to decide, we need to consider other effects, such as frequency detuning due to the heating and beam loading, since the therapy will take only ~1 s, and there will be no opportunity for automatic frequency control (Cha et al, 2017;Kim et al, 2019) during the operation. In the case of a SW accelerating cell structure, 18 MeV can be achieved in 20 cells, with a wall-losses of 500 kW of power per cell with.…”

Section: Frontiers In Medical Engineeringmentioning

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: Frontiers In Medical Engineeringmentioning

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 conventional linear accelerators using a magnetron, the frequency correcting range is about 0.9 MHz with 300 pulses per second repetition rate. Accordingly, in order to easily stabilizing the frequency by the AFC system, the maximum frequency shift of the cavity after applying the water cooling system should not exceed 450 kHz [8].…”

Section: Introductionmentioning

confidence: 99%

Multiphysics analysis of side-coupled RF cavity

Kejani¹,

Ghasemi²,

Davani³

et al. 2019

J. Inst.

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A: By changing the resonant frequency of the cavity due to the power dissipation in its wall, the impedance matching will impair and the power will reflect. The acceptable frequency shift range which is based on the cooling system in the cavity design depends on the ability of the automatic frequency controller system and the bandwidth of the RF amplifier output frequency. This paper describes how to couple electromagnetic, thermal and mechanical analysis and calculates the cavity frequency shift during operation. Multiphysics analysis investigations had done for an S-band side-coupled cavity. By using the Superfish code, the power loss ratio at different surfaces of the cavity could be accurately calculated and Steady-State Thermal (SST) analysis could be performed correctly. In this paper, the report on the simultaneous use of multiphysics analysis with the modules of the Ansys software is presented and the results of both simulations are compared. The temperature distribution of the cavity was obtained by using the Fluent software and its results were compared with the temperature distribution gained from applying the convection coefficient to the SST. Three cooling systems were investigated for different powers with different cross-sections. In this section of the investigation, after thermal analysis, deformed geometry was obtained due to thermal stresses. By electromagnetic analyzing of deformed geometry, its frequency shift was obtained for all different cases. In order to evaluate the simulations, after the construction of a single-cavity, frequency variations are measured in terms of temperature variation and the results are compared with each other. After constructing a single-cavity, frequency shifts based on temperature variations are measured and the results are compared with each other. K: Acceleration cavities and magnets superconducting (high-temperature superconductor; radiation hardened magnets; normal-conducting; permanent magnet devices; wigglers and undulators); Accelerator modelling and simulations (multi-particle dynamics; single-particle dynamics);

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The automatic frequency control based on artificial intelligence for compact particle accelerator

Kim

Ghergherehchi

Shin

et al. 2019

Review of Scientific Instruments

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In this work, an advantage actor critic (A2C) based intelligent automatic frequency control (AFC) system was developed for X-band linear accelerator (LINAC). A2C is one type of reinforcement learning, which indicates how software agents should perform actions in an environment. In this paper, the A2C based AFC algorithm and its environment design, simulation result, and controller hardware and software processes are described. The objective of our design is to match LINAC and magnetron frequency, and it is implemented via reward shaping using comparison with the reflected power in the adjacent time. The simulation with the A2C algorithm was implemented in two modes, namely, periodic and White Gaussian Noise (WGN) waves, for analysis with temperature and random disturbance, respectively. In order to create artificial disturbance in the experiment, the magnetron shaft was shifted randomly every 0.5 s by using WGN with 18° angle of the step motor. The standard deviation of the reflected power was 5.63 kW, and the average power was 130.9 kW. To obtain maximum reward at the beginning of the A2C training, the adjacent frequency is needed. The measured average reflected power and standard deviation were 122.8 kW and 1.75 kW, respectively, after 2000 iterations. The results show that the reflected power and standard deviation of the AFC with A2C were lower compared to open-loop with artificial disturbance. The RF station of a medical X-band LINAC was used as the test bench, and the performance was confirmed by the results of an experiment conducted at Sungkyunkwan University in Korea.

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Development of an automatic frequency control system for an X-band (=9300 MHz) RF electron linear accelerator

Cited by 4 publications

References 8 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

Multiphysics analysis of side-coupled RF cavity

The automatic frequency control based on artificial intelligence for compact particle accelerator

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