Niobium resonator development for high-brightness ion beam acceleration

The general steps for the fabrication of a copper prototype of 325 MHz coaxial half-wave resonator (HWR) with β = 0.21 are presented and discussed in this work. The main features for the control of the electromagnetic properties during the manufacturing process of HWR are described in detail. The resonant frequency sensitivity to the accelerating gap and to the cavity height were experimentally estimated. Bead-pull measurements were performed and the electric field distribution along the beam axis of the manufactured cavity was estimated. The features of the cavity’s response in the critical coupling regime are analyzed. The experimental concept of a slow frequency tuning system (FTS) based on the moving plungers is proposed and tested. The tuning sensibility is experimentally estimated. The measured results agree with the simulations quite well, and the sensitivity for a single plunger configuration Δ f / Δ L = + 13 kHz mm−1 is achieved. The dynamic properties and operation algorithm of the FTS are studied and experimentally investigated.

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“…The HWR-325 cavity was designed in classical coaxial HWR (figure 1(a)) configuration with integrated helium vessel [4,18].…”

Section: Cavity Designmentioning

confidence: 99%

Control of electromagnetic properties during prototyping, fabrication and operation of low-β 325 MHz half-wave resonators

Bychanok¹,

Sukhotski²,

Huseu³

et al. 2021

J. Phys. D: Appl. Phys.

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“…Elliptical cavities are mainly used in the acceleration for high velocity beta particles. For the low-beta and medium-beta particles, the TEM class cavities are widely used to get a compact cavity structure, such as the spoke cavity [37] Half Wavelength Resonator [38] and Quarter Wavelength…”

Section: Cavity Fundamentals and The Critical Issues In Cavity Designmentioning

confidence: 99%

Investigation of an Ultrafast Harmonic Resonant RF Kicker

Huang

2016

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An Energy Recovery Linac (ERL) based multi-turn electron Circulator Cooler Ring (CCR) is envisaged in the proposed Jefferson Lab Electron Ion Collider (JLEIC) to cool the ion bunches with high energy (55 MeV), high current (1.5 A), high repetition frequency (476.3 MHz), high quality magnetized electron bunches. A critical component in this scheme is a pair of ultrafast kickers for the exchange of electron bunches between the ERL and the CCR. The ultrafast kicker should operate with the rise and fall time in less than 2.1 ns, at the repetition rate of ~10s MHz, and should be able to run continuously during the whole period of cooling. These -and-fall time being combined together, are well beyond the state-of-art of traditional pulsed power supplies and magnet kickers.To solve this technical challenge, an alternative method is to generate this high repetition rate, fast rise-and-fall time short pulse continuous waveform by summing several finite number of (co)sine waves at harmonic frequencies of the kicking repetition frequency, and these harmonic modes can be generated by the Quarter Wave Resonater (QWR) based multifrequency cavities. Assuming the recirculator factor is 10, 10 harmonic modes (from 47.63 MHz to 476.3 MHz) with proper amplitudes and phases, plus a DC offset are combined together, a continuous short pulse waveform ABSTRACT II with the rise-and-fall time in less than 2.1 ns, repetition rate of 47.63 MHz waveform can be generated. With the compact and matured technology of QWR cavities, the total cost of both hardware development and operation can be reduced to a modest level.Focuse on the technical scheme, three main topics will be discussed in this thesis: the synthetization of the kicking pulse, the design and optimization of the deflecting QWR multi-integer harmonic frequency resonator and the fabrication and bench measurements of a half scale copper prototype.In the kicking pulse synthetization part, we begin with the Fourier Series expansion of an ideal square pulse, and get a Flat-Top waveform which will give a uniform kick over the bunch length of the kicked electron bunches, thus the transverse emittance of these kicked electron bunches can be maintained. By using two identical kickers with the betatron phase advance of 180 degree or its odd multiples, the residual kick voltage wave slopes at the unkicked bunch position will be totally cancelled out. Flat-Top waveform combined with two kicker scheme, the transverse emittance of the cooling electron bunches will be conserved during the whole injection, recirculation, and ejection processes.In the cavity design part, firstly, the cavity geometry is optimized to get high transverse shunt impedance thus less than 100 W of RF losses on the cavity wall can be achieved for all these 10 harmonic modes. To support all these 10 harmonic modes, group of four QWRs are adopted with the mode distribution of 5:3:1:1. In the multi-frequency cavities such as the five-mode-cavity and the three-mode-cavity, tunings are required to achieve the design frequencies...

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“…According to the final fitting curve between f ∆ and E acc in Fig. 5, the Lorentz force detuning coefficient K L is -4.657 Hz/(MV/m) 2 . From the point of view of energy content, the frequency detuning is still acceptable if the accelerating gradient is less than 5 MV/m.…”

Section: Lorentz Force Detuning (Lfd) Effectmentioning

confidence: 99%

“…The Injector II of CADS is being designed and built by IMP. As shown in Superconducting (SC) coaxial HWR was first proposed and prototyped in the early 1990s [2].…”

Section: Introductionmentioning

confidence: 99%

Study on the frequency tuning of the half-wave resonator at IMP

He¹,

He²,

Yue³

et al. 2014

Chinese Phys. C

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A 162.5 MHz superconducting half-wave resonator (HWR) with geometry beta of 0.09 is being developed for Injector II of China Accelerator Driven Sub-critical System (CADS) Project at the Institute of Modern Physics (IMP). The HWR section composed of 16 HWR cavities will accelerate the proton beam from 2.1 MeV to 10 MeV. The RF and mechanical coupled analysis are essential in geometry design in order to predict the deformation of the cavity walls and the frequency shift caused by the deformation. In this paper, the detuning caused by both bath helium pressure and Lorentz force is analysed and a tuning system has been investigated and designed to compensate the detuning by deforming the cavity along the beam axis. The simulations performed with ANSYS code show that the tuning system can adjust and compensate the frequency drift due to external vibrations and helium pressure fluctuation during operation.

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Niobium resonator development for high-brightness ion beam acceleration

Cited by 9 publications

References 10 publications

Control of electromagnetic properties during prototyping, fabrication and operation of low-β 325 MHz half-wave resonators

Control of electromagnetic properties during prototyping, fabrication and operation of low-β 325 MHz half-wave resonators

Investigation of an Ultrafast Harmonic Resonant RF Kicker

Study on the frequency tuning of the half-wave resonator at IMP

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