To meet the requirements of developing separated function radio frequency quadruple (rfq) and upgrading the 1 MeV integral split ring rfq accelerator, an electron cyclotron resonance O(+) ion source and low energy beam transport (LEBT) system have been developed. Using two Einzel lenses to focus the beam, more than 6 mA O(+) peak beam current with energy of 22 keV can be easily obtained at the end of LEBT when the duty faction is at 1/6. The normalized root-mean-square emittance of 90% of the beam is about 0.12pi mm mrad. By changing the focusing power of lenses, the beam waist can be shifted from 80 mm before the beam diaphragm 2 to 80 mm after it. The experimental results will be presented in this article.
[Show abstract][Hide abstract] ABSTRACT: A set of new ion extraction electrodes have been designed for the permanent magnetic electron cyclotron resonance ion source at Peking University to improve beam quality and transmission. PBGUNS has been used to optimize the extraction electrodes and simulate the beam behavior at the extraction region. The experiments showed that with the new system, the beam half divergence angle can be less than 40 mrad and the normalized rms emittance is about 0.13pi mm mrad when the extracted current is 100 mA at 50 keV in pulse mode. The voltage of the suppression electrode has great effect on beam divergence. The effect of the microwave power and gas flow is also studied.
The Review of scientific instruments 02/2010; 81(2):02B715. DOI:10.1063/1.3277213 · 1.61 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: An electron cyclotron resonance (ECR) ion source is designed for the production of high-current ion beams of various gaseous elements. At the Peking University (PKU), the primary study is focused on developing suitable permanent magnet ECR ion sources (PMECRs) for separated function radio frequency quadrupole (SFRFQ) accelerator and for Peking University Neutron Imaging Facility. Recently, other kinds of high-intensity ion beams are required for new acceleration structure demonstration, simulation of fusion reactor material irradiation, aviation bearing modification, and other applications. So we expanded the ion beam category from O(+), H(+), and D(+) to N(+), Ar(+), and He(+). Up to now, about 120 mA of H(+), 83 mA of D(+), 50 mA of O(+), 63 mA of N(+), 70 mA of Ar(+), and 65 mA of He(+) extracted at 50 kV through a φ 6 mm aperture were produced by the PMECRs at PKU. Their rms emittances are less than 0.2 π mm mrad. Tungsten samples were irradiated by H(+) or He(+) beam extracted from this ion source and H∕He holes and bubbles have been observed on the samples. A method to produce a high intensity H∕He mixed beam to study synergistic effect is developed for nuclear material irradiation. To design a He(+) beam injector for coupled radio frequency quadruple and SFRFQ cavity, He(+) beam transmission experiments were carried out on PKU low energy beam transport test bench and the transmission was less than 50%. It indicated that some electrode modifications must be done to decrease the divergence of He(+) beam.
The Review of scientific instruments 02/2012; 83(2):02B905. DOI:10.1063/1.3669788 · 1.61 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: As an injector for the Separated Function RFQ (SFRFQ) accelerator, the Integral Split Ring Radio Frequency Quadrupole (ISR RFQ) accelerator was upgraded to achieve a higher beam current. The experiments on the RFQ accelerator indicated that the maximum accelerated O+ beam current could exceed 3.2 mA with an energy of 1.03 MeV and energy spread (FWHM) of 3.1%. The resultant beam is then transported through a 1-m-long magnetic triplet and finally accelerated to 1.654 MeV by the SFRFQ cavity. The beam conditions of the RFQ accelerator were carefully optimized to satisfy the requirements of the SFRFQ accelerator, and the combined accelerator was able to deliver 0.53 mA of O+ beam to the end of the beam line, which has sufficiently demonstrated the feasibility of the SFRFQ cavity.
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 02/2013; 701:273–277. DOI:10.1016/j.nima.2012.11.001 · 1.22 Impact Factor
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