Test results of 18 GHz ECR charge breeder for KEK–JAERI RNB facility

Jeong, Sohee; Oyaizu, M.; Tojyo, E.; Kawakami, H.; Ishiyama, H.; Miyatake, H.; Enomoto, K.; Watanabe, Yutaka; Katayama, Ichiro; Nomura, T.; Matsuda, M.; Osa, A.; Ichikawa, Shinichi

doi:10.1063/1.1699453

Cited by 13 publications

(5 citation statements)

References 4 publications

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“…The charge breeding time τ CB is traditionally experimentally quantified with the process which consists in generating a rising edge of the injected beam (1þ) with an electrostatic steerer and measuring the rise time of the charge bred (Nþ) signal [5][6][7][8]. To obtain a better signal-to-noise ratio, the response is usually averaged over several measurements, requiring a pulsing of the injected beam.…”

Section: Introductionmentioning

confidence: 99%

Charge breeding time investigations of electron cyclotron resonance charge breeders

Angot

Tarvainen

Thuillier

et al. 2018

Phys. Rev. Accel. Beams

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To qualify electron cyclotron resonance charge breeders, the method that is traditionally used to evaluate the charge breeding time consists in generating a rising edge of the injected beam current and measuring the time in which the extracted multicharged ion beam reaches 90% of its final current. It is demonstrated in the present paper that charge breeding times can be more accurately measured by injecting short pulses of 1 þ ions and recording the time resolved responses of Nþ ions. This method is used to probe the effect of the 1 þ ion accumulation in the plasma known to disturb the buffer gas plasma equilibrium and is a step further in understanding the large discrepancies reported in charge breeding times. The experiments are conducted injecting a 85 Rb þ ion beam into the Laboratoire de Physique Subatomique et de Cosmologie (LPSC) charge breeder operated with helium as a buffer gas. The time needed for the extraction of 90% of the multicharged ions in short pulse mode is found slightly shorter (9%) than the charge breeding time measured with the traditional method. The charge breeding efficiency is identical with both methods. The pulse width and amplitude of the 1þ injection pulses have been varied to study their influence on the Nþ response and temporal parameters are proposed to qualify the time response. The short pulse method can be used to study the influence of the ion source tuning parameters on the charge breeding temporal characteristics. For example, it is shown here that an increase of the minimum magnetic field strength of the LPSC charge breeder in the range 0.432-0.444 T improves the multicharged ion confinement in the electron cyclotron resonance plasma, and so increases the charge breeding efficiency. The short pulse method is also used to estimate the charge breeding efficiencies of radioactive Rb isotopes taking into account their half-lives and charge states. The neutron-rich heavy isotopes have short half-lives, which makes the charge state distributions shift to lower charge states and the estimated charge breeding efficiencies of high charge states being close to three times less in comparison to the stable ions.

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Section: Introductionmentioning

confidence: 99%

Charge breeding time investigations of electron cyclotron resonance charge breeders

Angot

Tarvainen

Thuillier

et al. 2018

Phys. Rev. Accel. Beams

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“…This result suggests that the charge breeding time is shorter than the lifetimes, which is consistent with the measured charge breeding time of the KEKCB. 4 We predict that ⑀ CB will be dependent on lifetime for lifetimes less than a few 100 ms.…”

Section: Charge Breeding Efficienciesmentioning

confidence: 98%

“…A preliminary report on the specifications of the KEKCB obtained at the test bench is given in Ref. 4. By using the KEKCB, several RNBs, as well as stable nuclear beams ͑SNBs͒, have been charged bred to A / q Ӎ 7.…”

Section: Introductionmentioning

confidence: 99%

KEKCB electron cyclotron resonance charge breeder at TRIAC

Imai

Jeong

Oyaizu

et al. 2008

Review of Scientific Instruments

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The KEKCB is an electron cyclotron resonance (ECR) ion source for converting singly charged ions to multicharged ones at Tokai Radioactive Ion Accelerator Complex. By using the KEKCB, singly charged gaseous and nongaseous ions were converted to multicharged ones of A/q approximately 7 with efficiencies of 7% and 2%, respectively. The conversion efficiency was found to be independent of the lifetime of the radioactive nuclei having lifetimes of the order of one second. Three collimators located at the entrance and the exit of the KEKCB defined the beam axis and facilitated beam injection. Grinding and washing the surfaces of aluminum electrode and plasma chamber dramatically reduced impurities originating from the ECR plasma of the KEKCB.

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“…The 18 GHz electron cyclotron resonance ion source (ECRIS) [5,6] located upstream of the linacs has made it possible for TRIAC to deliver heavy-ion beams of stable isotopes. A large emittance acceptance (291 mm mrad) of the SCRFQ for a continuous beam makes it possible to accelerate such beam particles with intensities of several ten microamperes.…”

Section: Introductionmentioning

confidence: 99%

Low-background prebunching system for heavy-ion beams at the Tokai radioactive ion accelerator complex

Okada

Niki

Hirayama

et al. 2012

Phys. Rev. ST Accel. Beams

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A novel beam-bunching technique has been implemented at a heavy-ion linear accelerator facility by installing a compact two-gap prebuncher and a multilayer beam chopper. A pulsed beam of 2 to 4 MHz, having kinetic energy up to 1:1 MeV=u, is realized by bunching a 2 keV=u continuous beam just upstream of the linac. Around 40% of the continuous beam particles are successively gathered in a single microbunch with a time width of around 15 ns in full width at one-tenth maximum. The number of background beam particles over 250 ns just before the bunched beam is well suppressed to less than 10 À4 of the number of bunched particles. This technique has been adopted to generate intense -particle beams for nuclear astrophysics experiments.

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Test results of 18 GHz ECR charge breeder for KEK–JAERI RNB facility

Cited by 13 publications

References 4 publications

Charge breeding time investigations of electron cyclotron resonance charge breeders

Charge breeding time investigations of electron cyclotron resonance charge breeders

KEKCB electron cyclotron resonance charge breeder at TRIAC

Low-background prebunching system for heavy-ion beams at the Tokai radioactive ion accelerator complex

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