Time-dependent potential functions to stretch the time distributions of ion pulses ejected from EBIST

Lapierre, A.

doi:10.1139/cjp-2016-0716

Cited by 10 publications

(6 citation statements)

References 15 publications

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“…With the axial potential set to 1.6 kV, the ion-cloud radius becomes the same as the electron-beam radius at the compensation ratio of 0.69. A Maxwell-Boltzmann distribution with 3-degree-of-freedom [10] was used for generating the initial ion energy distribution presented in Figure 2. A most probable ion kinetic energy per charge was set to be 10% of each axial potential, as 1.5Ti/q ≈ 0.1eVwell.…”

Section: Electron-and Ion-beam Simulationsmentioning

confidence: 99%

Progress of the High-Current EBIS Charge Breeder for the FRIB

Son

Lapierre

Villari

et al. 2022

J. Phys.: Conf. Ser.

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The ReA post-accelerator of the National Superconducting Cyclotron Laboratory employs an Electron-Beam Ion Trap (EBIT) as a charge breeder to reaccelerate rare-isotope beams to several MeV/u. The Facility for Rare-Isotope Beams (FRIB) is near completion and will provide RIB rates expected to exceed in some cases 1010 particles/s. The ReA EBIT operates with an electron current of 300 – 600 mA, corresponding to an electron current density of 170 – 340 A/cm2 and a maximum trap capacity of 1010 elementary charges, which can be insufficient to handle high FRIB rates. A High-Current Electron-Beam Ion Source (HCEBIS) has been constructed based on the backbones of the TEST EBIS from the Brookhaven National Laboratory. By using a 4-A electron beam, a current density of 298 A/cm2 and a maximum trap capacity of 2.4×10n elementary charges can be achieved. This paper presents the status of the HCEBIS. It also includes results of electron- and ion-beam simulations and discusses electron-beam commissioning plans.

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Section: Electron-and Ion-beam Simulationsmentioning

confidence: 99%

Progress of the High-Current EBIS Charge Breeder for the FRIB

Son

Lapierre

Villari

et al. 2022

J. Phys.: Conf. Ser.

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“…The energy distribution of 85 Rb 9+ ions inside the trap was measured with a method derived from [4]. The idea is to split the ion bunch into two components by using a three-level extraction function: trap closed (V = V high ), partially open (V = V p ) over a time t p , and open (V = V low ).…”

Section: Energy Distribution Measurementsmentioning

confidence: 99%

Pulse-stretching out of the CANREB EBIS

Cavenaile,

Charles,

Kester

et al. 2024

J. Phys.: Conf. Ser.

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The CANadian Rare isotope facility with Electron-Beam ion source (CANREB) at TRIUMF is set to deliver rare isotope beams in high charge states. In the Electron Beam Ion Source (EBIS) ions are charge-bred by collisions with an electron beam of up to 500 mA. A strong magnetic field (up to 6T) maximizes the overlap between ions and electron beam and increases the breeding efficiency. Ion confinement is maintained by a combination of an electrostatic field and the electron beam space-charge potential. Ions are released by lowering the trapping potential with a step function. The system is operated at a pulse repetition frequency up to 100 Hz. Due to the short trap length, this fast extraction scheme produces pulses shorter than 10 µs with high instantaneous rates that can saturate detectors in experiments. Stretching the pulse can be done using a slowly varying voltage function to modify trap electrode potentials instead of a step function. The ideal function produces a pulse with a flat top distribution and can be calculated by knowing the ion energy distribution inside the trap. The latest pulse-stretching results will be discussed including the latest pulse duration up to 1.4 ms that have been produced. The slow extraction scheme has also been used for a measurement of the effective energy distribution of the ions inside the trap.

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“…Stretching the pulses can be accomplished by lowering the ejection barrier potential over a long time period with a time-dependent voltage function resembling a ramp. Theoretical studies were conducted in [35] and test results using this stretching scheme were presented in [21,30]. Highly charged ions produced from injected and residual gas, 84 Kr 26þ and 40 Ar 16þ , respectively, were used for these tests by detecting ions with an MCP located after the Q=A separator.…”

Section: Stretching Of Ejected Ion Pulsesmentioning

confidence: 99%

“…Ar 17þ and 46 K 18þ ejected with a linear function over 120 ms were observed to exit the trap within a narrow distribution of approximately 10-20 ms half-way or over the last portion of the ramp. To maximize the ion spread (and make efficient use of the time available for ejection), the barrier potential has to be first lowered rapidly at the beginning of the ejection time to reach the maximum of the energy distribution in the trapping potential [35]. Then, the lowering rate must be reduced for a slow release of ions as needed.…”

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confidence: 99%

First two operational years of the electron-beam ion trap charge breeder at the National Superconducting Cyclotron Laboratory

Lapierre

Bollen

Crisp

et al. 2018

Phys. Rev. Accel. Beams

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The electron-beam ion trap (EBIT) charge breeder of the ReA post-accelerator, located at the National Superconducting Cyclotron Laboratory (Michigan State University), started on-line operation in September 2015. Since then, the EBIT has delivered many pilot beams of stable isotopes and several rare-isotope beams. An operating aspect of the ReA EBIT is the breeding of high charge states to reach high reaccelerated beam energies. Efficiencies in single charge states of more than 20% were measured with 39 K 15þ , 85 Rb 27þ , 47 K 17þ , and 34 Ar 15þ. Producing high charge states demands long breeding times. This reduces the ejection frequency and, hence, increases the number of ions ejected per pulse. Another operating aspect is the ability to spread the distribution in time of the ejected ion pulses to lower the instantaneous rate delivered to experiments. Pulse widths were stretched from a natural 25 μs up to ∼70 ms. This publication reviews the progress of the ReA EBIT system over the years and presents the results of charge-breeding efficiency measurements and pulse-stretching tests obtained with stable-and rare-isotope beams. Studies performed with high sensitivity to identify and quantify stable-isotope contaminants from the EBIT are also presented, along with a novel method for purifying beams.

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Time-dependent potential functions to stretch the time distributions of ion pulses ejected from EBIST

Cited by 10 publications

References 15 publications

Progress of the High-Current EBIS Charge Breeder for the FRIB

Progress of the High-Current EBIS Charge Breeder for the FRIB

Pulse-stretching out of the CANREB EBIS

First two operational years of the electron-beam ion trap charge breeder at the National Superconducting Cyclotron Laboratory

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