Comparison of longitudinal emittance of various RFQs

Comunian, M.; Bellan, L.; Pisent, A.

doi:10.1088/1748-0221/19/01/p01024

Cited by 4 publications

(3 citation statements)

References 10 publications

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“…We continue to study the dependency of the initial input distribution on the RF field in the RFQ. Since our challenges are the beam dynamics in the strong space charge force, the beam transport is being discussed carefully, including its dependency on the longitudinal [16] and transverse emittances given by the beam-RFQ field interaction.…”

Section: Discussionmentioning

confidence: 99%

Measurements of momentum halo due to the reduced RFQ voltage during the LIPAc beam commissioning

Hirosawa,

Bellan,

Benedetti

et al. 2024

J. Inst.

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The Linear IFMIF Prototype Accelerator, LIPAc, is being commissioned aiming at validating the RFQ up to 5 MeV beam acceleration. Eventually, the nominal beam of 5 MeV–125 mA in 1 ms length and 1 Hz rate pulsed mode was achieved in 2019. The beam operation has been resumed since July 2023 after a long maintenance including recovery from unexpected problems in the RFQ-RF system. This new phase aims at the commissioning of the full configuration except SRF LINAC, which is replaced by a temporary beam transport line. Focusing on the RFQ behavior, it will be interesting to operate it at higher duty, especially for longer pulses. Furthermore, a beam simulation study suggested that the beam extracted from the RFQ includes considerable momentum halo when the vane voltage reduces by more than 5 %, with a slight decrease of the mean energy. It can be a potential source of a quench like the mismatched beam in the cryomodule. This could be studied by measuring the energy from the Time-of-Flight among multiple BPMs while monitoring beam loss around the dipole, where momentum halo should be lost. During the beam commissioning phase, we studied them by scanning the RFQ voltage.

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Section: Discussionmentioning

confidence: 99%

Measurements of momentum halo due to the reduced RFQ voltage during the LIPAc beam commissioning

Hirosawa,

Bellan,

Benedetti

et al. 2024

J. Inst.

Self Cite

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“…The longitudinal emittance for the input SART beam is higher even after transport line re-matching. This is due to the fact that since the RFQ is designed for higher beam current, low proton fraction causes filamentation in longitudinal phase space, thereby causing higher longitudinal emittance [14,15]. In the case of transverse emittance, the rms beam emittance and Twiss parameters of the input SART beam are different from the original LEHIPA simulations and hence the matched SART beam shows different emittance characteristics.…”

Section: Beam Dynamics Studiesmentioning

confidence: 99%

“…With the beam composition changing over time, it becomes important to characterise the beam at different proton fraction levels to understand the longitudinal and transverse beam dynamics. Since the RFQ is designed for a higher beam current, a reduction in the input beam current leads to filamentation in the longitudinal phase space and this has been experimentally observed in beam energy spread measurements at LEHIPA [7,14,15]. This phenomenon causes an increase in the longitudinal emittance and hence the medium energy beam transport (MEBT) line parameters, especially the double gap rebunching cavity voltage, need to be re-optimized to reduce the longitudinal emittance growth.…”

Section: Introductionmentioning

confidence: 99%

Phase space reconstruction technique for beam optimization in the Low Energy High Intensity Proton Accelerator (LEHIPA)

Priyadarshini,

Mathew,

Mathad

et al. 2024

Phys. Scr.

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The Low Energy High Intensity Proton Accelerator (LEHIPA) has been commissioned to the design energy of 20 MeV at BARC, India. The low energy beam transport (LEBT) channel of LEHIPA consists of two solenoids and drift spaces for matching the 50 keV proton beam from the ECR ion source (ECR-IS) to the RFQ. The ion beam extracted from the ECR-IS also contains molecular species like H2+ and H3+. Proton fraction in the beam is found to degrade slowly with time due to surface contamination of the plasma chamber and this reduction in proton beam current has implications for longitudinal and transverse beam dynamics. Hence, it becomes important to characterise the beam at different proton fraction levels to understand the end-to-end beam dynamics of LEHIPA. Computed Tomography (CT) technique has been used for the beam phase-space reconstruction in LEHIPA, using a Python program, incorporating the feature of filtering secondary species from the beam profiles measured using slit scanners in the LEBT. Simultaneous Algebraic Reconstruction Technique (SART) is used in the reconstruction since it is identified to be a better technique for a limited number of projections. The reconstruction program is benchmarked with the TraceWin beam dynamics code and implemented on the measured beam profiles to recreate the phase space distribution at the beginning of LEBT. Further, the tomographic reconstruction method is compared with the solenoid scan method and the rms emittance values are found to be in good agreement. The measured tomographic phase space distribution has then been used as TraceWin input for LEHIPA end-end beam dynamics simulations and the LEHIPA beam line parameters are re-optimized for minimum beam emittance growth. This paper presents the simulations of CT technique, benchmarking simulations with TraceWin, phase space reconstruction with measured beam profiles and beam dynamics studies of LEHIPA using the reconstructed beam distributions.

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Beam dynamics design and error analysis of a high frequency RFQ for medical application

Liu,

Gu,

Yuan

et al. 2024

Nuclear Instruments and Methods in Physics Research Section A:

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Comparison of longitudinal emittance of various RFQs

Cited by 4 publications

References 10 publications

Measurements of momentum halo due to the reduced RFQ voltage during the LIPAc beam commissioning

Measurements of momentum halo due to the reduced RFQ voltage during the LIPAc beam commissioning

Phase space reconstruction technique for beam optimization in the Low Energy High Intensity Proton Accelerator (LEHIPA)

Beam dynamics design and error analysis of a high frequency RFQ for medical application

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