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Title: Investigations of the output energy deviation and other parameters during commissioning of the four-rod radio frequency quadrupole at the Fermi National Accelerator Laboratory

Abstract

After 30 years of operation, the Cockcroft-Walton based injector at FNAL (Fermi National Accelerator Laboratory) has been replaced by a new beam line including a dimpled magnetron 35 keV source in combination with a 750 keV 4-rod Radio Frequency Quadrupole (RFQ). The new injector is followed by the existing drift tube linac (DTL). Prior to installation, a test beam line was built which included the magnetron source and the 4-rod RFQ with a number of beam measurement instrumentation. The first beam test with the RFQ showed an output energy deviation greater than 2.5%. Other problems also showed up which led to investigations of the output energy, power consumption and transmission properties using RF simulations which were complemented with additional beam measurements. The sources of this deviation and the mechanical modifications of the RFQ to solve this matter will be presented in this paper. Meanwhile, the nominal output energy of 750 keV has been confirmed and the new injector with the 4-rod RFQ is in full operation.

Authors:
;
Publication Date:
Research Org.:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
OSTI Identifier:
1151739
Report Number(s):
FERMILAB-PUB-14-095-AD
Journal ID: ISSN 1098-4402; PRABFM; ArticleNumber: 030102
DOE Contract Number:
AC02-07CH11359
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Special Topics - Accelerators and Beams; Journal Volume: 17; Journal Issue: 3
Country of Publication:
United States
Language:
English

Citation Formats

Schmidt, J. S., and et al.,. Investigations of the output energy deviation and other parameters during commissioning of the four-rod radio frequency quadrupole at the Fermi National Accelerator Laboratory. United States: N. p., 2014. Web. doi:10.1103/PhysRevSTAB.17.030102.
Schmidt, J. S., & et al.,. Investigations of the output energy deviation and other parameters during commissioning of the four-rod radio frequency quadrupole at the Fermi National Accelerator Laboratory. United States. doi:10.1103/PhysRevSTAB.17.030102.
Schmidt, J. S., and et al.,. 2014. "Investigations of the output energy deviation and other parameters during commissioning of the four-rod radio frequency quadrupole at the Fermi National Accelerator Laboratory". United States. doi:10.1103/PhysRevSTAB.17.030102. https://www.osti.gov/servlets/purl/1151739.
@article{osti_1151739,
title = {Investigations of the output energy deviation and other parameters during commissioning of the four-rod radio frequency quadrupole at the Fermi National Accelerator Laboratory},
author = {Schmidt, J. S. and et al.,},
abstractNote = {After 30 years of operation, the Cockcroft-Walton based injector at FNAL (Fermi National Accelerator Laboratory) has been replaced by a new beam line including a dimpled magnetron 35 keV source in combination with a 750 keV 4-rod Radio Frequency Quadrupole (RFQ). The new injector is followed by the existing drift tube linac (DTL). Prior to installation, a test beam line was built which included the magnetron source and the 4-rod RFQ with a number of beam measurement instrumentation. The first beam test with the RFQ showed an output energy deviation greater than 2.5%. Other problems also showed up which led to investigations of the output energy, power consumption and transmission properties using RF simulations which were complemented with additional beam measurements. The sources of this deviation and the mechanical modifications of the RFQ to solve this matter will be presented in this paper. Meanwhile, the nominal output energy of 750 keV has been confirmed and the new injector with the 4-rod RFQ is in full operation.},
doi = {10.1103/PhysRevSTAB.17.030102},
journal = {Physical Review Special Topics - Accelerators and Beams},
number = 3,
volume = 17,
place = {United States},
year = 2014,
month = 3
}
  • A project to study a new type of acceleration structure has been launched at Peking University, in which a traditional radio frequency quadrupole (RFQ) and a separated function radio frequency quadrupole are coupled in one cavity to accelerate the He+ beam. A helium injector for this project is developed. The injector consists of a 2.45 GHz permanent magnet electron cyclotron resonance ion source and a 1.16 m long low energy beam transport (LEBT). The commissioning of this injector was carried out and an onsite test was held in June 2013. A 14 mA He+ beam with the energy of 30more » keV has been delivered to the end of the LEBT, where a diaphragm with the diameter of 7 mm is located. The position of the diaphragm corresponds to the entrance of the RFQ electrodes. The beam emittance and fraction were measured after the 7 mm diaphragm. Its rms emittance is about 0.14 π mm mrad and the fraction of He+ is about 99%.« less
  • The low energy beam transport system (LEBT) for the National Spallation Neutron Source is required to transport 35 mA of a 65 keV H{sup {minus}} ion beam from the ion source to the radio frequency quadrupole accelerator (RFQ) entrance with a normalized root-mean-square emittance {lt} 0.15 pi mm mrad. At a later time, it is anticipated that this beam current will be increased to 70 mA. For this purpose a radio-frequency driven, magnetically filtered multicusp ion source is under development at LBNL. The H{sup {minus}} beam extraction from the ion source is being simulated utilizing the three-dimensional (3D) computer codemore » ARGUS. H{sup {minus}} ion beam extraction from the ion source requires proper simulation of the extraction of both plasma electrons and the desired H{sup {minus}} ions. The goal is to optimize the LEBT system so that the electrons are completely deflected between the first two electrodes and the desired H{sup {minus}} beam is properly matched into the RFQ accelerator. The magnetic field in the extraction region is being optimized by using the 3D magnetic code OPERA3D. The performance of the all electrostatic LEBT for the transport of higher currents ({gt}70 mA) is discussed. {copyright} {ital 1998} {ital American Institute of Physics}« less
  • The Fermi National Accelerator Laboratory (FNAL) 40 year old Cockcroft-Walton 750 keV injectors with slit aperture magnetron ion sources have been replaced with a circular aperture magnetron, Low Energy Beam Transport, Radio Frequency Quadrupole Accelerator, and Medium Energy Beam Transport, as part of the FNAL Proton Improvement Plan. The injector design is based on a similar system at Brookhaven National Laboratory. The installation, commissioning efforts, and source operations to date will be covered in this paper along with plans for additional changes to the original design to improve reliability by reducing extractor spark rates and arc current duty factor.