J.Y. Li, T. Hu, J. Yang, B.Q. Zeng
HUST, Wuhan, People’s Republic of China
H.G. Xu
SINR, Jiading, Shanghai, People’s Republic of China
Funding:This work was supported by National Natural Science Foundation of China (NSFC) under Project Numbers 11905074. Electron linear accelerators with an energy of ~MeV are widely required in industrial applications. Whereas miniaturized accelerators, especially those working at X-band, attract more and more attention due to their compact structures and high gradients. Since the performance of a traveling wave (TW) accelerator is determined by its structures, considerable efforts must be made for structure optimization involving numerous and complex parameters. In this context, functional key parameters are obtained through deep analysis for structure and particle motion characteristics of the TW accelerator, then a multi-objective genetic algorithm (MOGA) is successfully applied to acquire an optimized phase velocity distribution which can contribute to achieving a high capture ratio and a low energy spread. Finally, a low-energy X-band TW tube used for rubber vulcanization is taken as an example to verify the reliability of the algorithm under a single-particle model. The capture ratio is 91.2%, while the energy spread is 5.19%, and the average energy is 3.1MeV.
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C.M. Bhat, S. Chaurize, P. Derwent, M.W. Domeier, V.M. Grzelak, W. Pellico, J. Reid, B.A. Schupbach, C.-Y. Tan, A.K. Triplett
Fermilab, Batavia, Illinois, USA
Funding:This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. The Fermilab Booster is the oldest RCS in operation in the world. In current operations, it accelerates ~4.5E12ppp to 8 GeV at 15 Hz and will be upgraded to >6.7E12ppp at 20 Hz in the PIP-II era. Booster has 22 RF cavities with each capable of providing ~50 kV. These cavities are divided into two groups: A & B. In the tunnel, the cavities are cavities are placed in a BA, AB, ¿ sequence. At injection, A & B cavities have anti-parallel RF phase which results in a net zero RF voltage on the beam. During beam capture, the RF voltage is increased adiabatically by decreasing the relative phase between them. At the end of beam capture, the feedback is turned on for beam acceleration. It is vital that for current operations and in the PIP-II era that these cavities are properly matched in both magnitude and phase to preserve the longitudinal emittance during the early part of the beam cycle and to offer full RF voltage on the beam. In this paper we describe the how the cavities are distributed and how the phases are measured with beam and then corrected and balanced. Data with high intensity beam capture is also presented.
M. El Baz
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
J.-P. Carneiro, B.M. Hanna
Fermilab, Batavia, Illinois, USA
The PIP-II particle accelerator is a new upgrade to the Fermilab accelerator complex, featuring an 800-MeV H⁻ superconducting linear accelerator that will inject the beam into the present Fermilab Booster. A test accelerator known as PIP-II Injector Test (PIP2IT) has been built to validate the concept of the front-end of PIP-II. One of the paramount challenges of PIP2IT was to demonstrate a low longitudinal emittance at the end of the front end. Having a low longitudinal emittance is crucial in order to ensure the stability of the beam in the accelerator. We present a longitudinal emittance calculation at 14.3 MeV at the SSR1-8 cavity in the High Energy Transport line (HEBT). The signal is collected by a Fast Faraday Cup (FFC) at the end of HEBT and recorded by a high-bandwidth oscilloscope.
B. Yee-Rendón, Y. Kondo, F. Maekawa, S.I. Meigo, J. Tamura
JAEA/J-PARC, Tokai-mura, Japan
The Japan Atomic Energy Agency (JAEA) is working in the research and development of an Accelerator Driven Subcritical System (ADS) for the transmutation of nuclear waste. To this end, JAEA is designing a 30-MW cw proton linear accelerator (linac) with a beam current of 20 mA. The JAEA-ADS linac starts with a Normal Conducting (NC) up to an energy of 2.5 MeV. Then, five Superconducting (SC) sections accelerate the beam up to 1.5 GeV. The biggest challenge for this ADS linac is the stringent reliability required to avoid thermal stress in the subcritical reactor, which is higher than the achieved in present accelerators. For this purpose, the linac pursues a strong-stable design that ensures the operation with low beam loss and fault-tolerance capabilities to continue operating in case of failure. This work presents the beam dynamics results toward achieving high reliability for the JAEA-ADS linac.
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A. Lasheen, H. Damerau, K. Iliakis
CERN, Meyrin, Switzerland
In the context of the LHC Injector Upgrade (LIU) project, the main longitudinal limitations in the CERN PS are coupled bunch instabilities and uncontrolled emittance blow-up leading to losses at injection into the downstream accelerator, the SPS. To complement beam measurements, particle tracking simulations are an important tool to study these limitations. However, to avoid excessive runtime, simulations are usually targeting only a fraction of the cycle assuming that bunches are initially matched to the RF bucket. This ignores all initial perturbations that could seed an instability. Simulations were therefore performed along the full PS cycle by using the BLonD tracking code optimized with advanced parallelization schemes. They include beam manipulations with several RF harmonics (batch compression, merging, splittings), controlled emittance blow-up, a model of the beam coupling impedance covering a wide frequency range, as well as beam and cavity feedbacks. A large number of macroparticles is required as well as arrays to store beam induced voltage spanning several revolutions to account for long range wakefields.
A. Gatera, J. Belmans, S. Boussa, F. Davin, W. De Cock, V.R.A. De florio, F. Doucet, L. Parez, F. Pompon, A. Ponton, D. Vandeplassche, E. Verhagen
SCK•CEN, Mol, Belgium
Dr. Ben Abdillah, C. Joly, L. Perrot
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
F. Bouly, E. Froidefond, A. Plaçais
LPSC, Grenoble Cedex, France
H. Podlech
IAP, Frankfurt am Main, Germany
J. Tamura
JAEA/J-PARC, Tokai-mura, Japan
C. Zhang
GSI, Darmstadt, Germany
The MYRRHA project at SCK•CEN, Belgium, aims at coupling a 600 MeV proton accelerator to a subcritical fission core operating at a thermal power of 60 MW. The nominal proton beam for this ADS has an intensity of 4 mA and is delivered in a quasi-CW mode. MYRRHA’s linac is designed to be fault tolerant thanks to redundancy implemented in parallel at low energy and serially in the superconducting linac. Phase 1 of the project, named MINERVA, will realise a 100 MeV, 4 mA superconducting linac with the mission of demonstrating the ADS requirements in terms of reliability and of fault tolerance. As part of the reliability optimisation program the integrated prototyping of the MINERVA injector is ongoing at SCK•CEN in Louvain-la-Neuve, Belgium. The injector test stand aims at testing sequentially all the elements composing the front-end of the injector. This contribution will highlight the beam dynamics choices in MINERVA’s injector and their impact on ongoing commissioning activities. *angelique.gatera@sckcen.be
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