Electron Beam Ion Source Trap Research Articles

Cluster ion source for external injection and high capacity filling of light elements into the relativistic heavy ion collider electron beam ion source.

An advanced Electron Beam Ion Source (EBIS) is the primary ion source to supply highly charged ion beams of different elements to the Relativistic Heavy Ion Collider (RHIC) and to the NASA Space Radiation Laboratory (NSRL). Intense beams of highly charged ions of various elements of the periodic table, ranging from helium to uranium, have been demonstrated since EBIS became operational in 2010. EBIS routinely provides ion beams to RHIC and NSRL quasisimultaneously with about 1 s switching time between different ion species. Such unique flexibility and rapid switching between ion species are based on external injection of singly charged ions into the EBIS trap either in "fast" or "slow" injection modes. At present, a Laser Ion Source (LIS) provides most of the ion species of solid materials using the "fast" injection mode into the EBIS trap and a Hollow Cathode Ion Source (HCIS) provides most of the ion species of gaseous elements using the "slow" injection mode into the EBIS trap. Gas injection into the EBIS trap is also possible and has been used but imposes some restrictions for the simultaneous generation of highly charged ions such as Au32+ ions for RHIC and ions of gaseous species for NSRL. Because light ions have relatively high velocity inside the EBIS trap, efficient injection of hydrogen and helium ions and filling of the EBIS trap to high capacity is difficult from either LIS or HCIS. To overcome this restriction and enhance EBIS operational capability, we suggest injecting beams of hydrogen and helium cluster ions into the EBIS trap. Required parameters of cluster ion beam injection into the EBIS trap are estimated, and advantages of such an injection are highlighted. A cluster ion source with required high intensity is visible and will be designed, built, optimized, and tested.

Universal main magnetic focus ion source: A new tool for laboratory research of astrophysics and Tokamak microplasma

A novel room-temperature ion source for the production of atomic ions in electron beam within wide ranges of electron energy and current density is developed. The device can operate both as conventional Electron Beam Ion Source/Trap (EBIS/T) and novel Main Magnetic Focus Ion Source. The ion source is suitable for generation of the low-, medium- and high-density microplasma in steady state, which can be employed for investigation of a wide range of physical problems in ordinary university laboratory, in particular, for microplasma simulations relevant to astrophysics and ITER reactor. For the electron beam characterized by the incident energy Ee = 10 keV, the current density je ∼ 20 kA/cm2 and the number density ne ∼ 2 × 1013 cm−3 were achieved experimentally. For Ee ∼ 60 keV, the value of electron number density ne ∼ 1014 cm−3 is feasible. The efficiency of the novel ion source for laboratory astrophysics significantly exceeds that of other existing warm and superconducting EBITs.

Room-temperature EBIS/T developments: past, present and future

We present a brief overview of the Dresden Electron Beam Ion Source/Trap (EBIS/T) family focusing on the advantages and limits of different types of permanent magnet systems for electron beam compression. The advanced electron optics of these sources as well as the operating parameters of the Dresden EBIT, EBIS, and EBIS-A are discussed. Furthermore, the recently commissioned Dresden EBIS-SC is introduced. Using a liquid helium free superconducting magnet system it stands out as a new kind of the Dresden EBIS/T ion source family as a compact and powerful electron beam ion source.

SPARC EBIT — a charge breeder for the HITRAP project

Charge breeding of externally injected, singly-charged ions in an electron beam ion source/trap (EBIS/T) extends the range of elements from which highly-charged ions can be produced with these machines, which is important for numerous atomic and nuclear physics experiments. Existing EBIS/T charge breeders feature electron guns producing intense beams and superconducting magnets generating strong fields to achieve high efficiencies and high ion charge states. We show an alternative possibility to inject, capture, charge-breed and extract ions using a compact room-temperature EBIT based on permanent magnet technology. Singly-charged potassium and rubidium ions injected over the barrier were charge bred and extracted as bare and neon-like ions, respectively. Simulations of injection and capture of singly-charged ions in this EBIT show the challenges and help understanding the results.

EBIS/T charge breeding for intense rare isotope beams at MSU

Experiments with reaccelerated beams are an essential component of the science program of existing and future rare isotope beam facilities. NSCL is currently constructing ReA3, a reaccelerator for rare isotopes that have been produced by projectile fragmentation and in-flight fission and that have been thermalized in a gas stopper. The resulting low-energy beam will be brought to an Electron Beam Ion Source/Trap (EBIS/T) in order to obtain highly charged ions at an energy of 12 keV/u. This charge breeder is followed by a compact linear accelerator with a maximum beam energy of 3 MeV/u for 238U and higher energies for lighter isotopes. Next-generation rare isotope beam facilities like the Facility for Rare Isotope Beams FRIB, but also existing Isotope Separator On-line (ISOL) facilities are expected to provide rare-isotope beam rates in the order of 1011 particles per second for reacceleration. At present the most promising scheme to efficiently start the reacceleration of these intense beams is the use of a next-generation high-current charge-breeder based on an EBIS/T. MSU has formed a collaboration to develop an EBIT for this purpose. A new high-current EBIS/T breeder will be developed and constructed at MSU, where also first tests on achievable beam rate capability will be performed. The EBIT is planned to be installed at the Isotope Separator and Accelerator facility ISAC at TRIUMF laboratory for on-line tests with rare isotope beams and to provide intense energetic reaccelerated radioactive beams. The status of the ReA3-EBIS/T in the NSCL reaccelerator project is given with a brief summary of results, followed by a discussion of plans for the future high-intensity EBIS/T charge breeder.

Model simulations of continuous ion injection into electron-beam ion source trap with slanted electrostatic mirror

The efficiency of trapping ions in an electron-beam ion source (EBIS) is of primary importance for many applications requiring operations with externally produced ions: RIA breeders, ion sources, and traps. At the present time, the most popular method of ion injection is pulsed injection, when short bunches of ions get trapped in a longitudinal trap while traversing the trap region. Continuous trapping is a challenge for EBIS devices because mechanisms which reduce the longitudinal ion energy per charge in a trap (cooling with residual gas, energy exchange with other ions, and ionization) are not very effective, and accumulation of ions is slow. A possible approach to increase trapping efficiency is to slant the mirror at the end of the trap which is opposite to the injection end. A slanted mirror will convert longitudinal motion of ions into transverse motion, and, by reducing their longitudinal velocity, prevent these ions from escaping the trap on their way out. The trade-off for the increased trapping efficiency this way is an increase in the initial transverse energy of the accumulated ions. The slanted mirror can be realized if the ends of two adjacent electrodes, drift tubes, which act as an electrostatic mirror, are machined to produce a slanted gap, rather than an upright one. Applying different voltages to these electrodes will produce a slanted mirror. The results of two-dimensional (2D) and three-dimensional (3D) computer simulations of the ion injection into an EBIS are presented using simplified models of an EBIS with conical (2D simulations) and slanted (3D simulations) mirror electrodes.

BRICTEST: a code for charge breeding simulations in RF quadrupolar field

In the framework of the SPES project (Study for Production of Exotic Species), funded by Istituto Nazionale Fisica Nucleare (INFN) at the Laboratori Nazionali Legnaro (LNL) (Padua) for Radioactive Ion Beam (RIB) production, an R&D experiment of a charge breeder device, called BRIC (BReeding Ion Charge), is in progress at LNL. BRIC is an Electron Beam Ion Source (EBIS) type ion charge state breeder in which a radio frequency (RF) quadrupolar field has been superimposed in the trapped ion region to introduce a selective containment with the aim of increasing the wanted ion trapping efficiency. A code that studies the motion and the ion charge state evolution in the trap region of the BRIC device has been recently developed in the Bari INFN section. That code has the aim of showing if, in the presence of an axial magnetic field and electron beam space charge force, the RF quadrupole field can still give a selective ion containment in the EBIS trap region. The code, furthermore, should allow choosing the RF quadrupole parameters to optimize the ion charge containment efficiency. In this paper the main feature of the code, named BRICTEST, and the simulation test will be presented and shortly discussed.

Charge breeding techniques

The numerous newly built and forthcoming post-accelerators for radioactive ions, produced with the isotope separator on-line (ISOL) technique, all have a need for an efficient method to accelerate the precious primary ions. By increasing the ion charge-tomass ratio directly after the radioactive ion production stage, a short and compact linear accelerator can be employed. Not only the efficiency, but also the rapidity of such a charge-to-mass increasing process, called charge breeding, is a crucial factor for the often short-lived radioisotopes. The traditional foil or gas stripping technique was challenged some five to ten years ago by novel schemes for charge breeding. The transformation from 1 + to n + charged ions takes place inside an Electron Beam Ion Source/Trap (EBIS/T) or Electron Cyclotron Resonance Ion Source/Trap (ECRIS/T) by electron-ion collisions. These charge breeders are located in the low-energy part of the machine before the accelerating structures. Because of the capability of these devices to produce highly charged ions, mass-to-charge ratios between 4 and 9 are easily obtained. In this article the performance and the features of the above listed charge breeding concepts will be compared and discussed. An outlook on charge breeders for the next generation of radioactive ion beam facilities is also given.

Recent results with Au ions from a multiampere electron beam ion source at Brookhaven National Laboratory (invited abstract)

An electron beam ion source (EBIS) that would satisfy Relativistic Heavy Ion Collider (at Brookhaven National Laboratory) (RHIC) requirements should be capable of producing intensities of, e.g., Au32+ ions of about 3×109 particles/pulse in 10–40 μs pulses. The total charge extracted (all charge states) would be 85 nC, assuming 20% in the peak charge state. To achieve this at Brookhaven National Laboratory, pulsed-electron beam currents up to 10 A, 100 ms are being used. A test EBIS has been constructed, designed for the full electron beam power and having close to half of the trap length of an EBIS for RHIC. As a result of successful experiments on the test EBIS, we are confident that an EBIS meeting RHIC requirements can be built. Initial electron beam tests have demonstrated a 100 ms, 8.6 A electron beam through the EBIS trap. The stable operation of 10 A, 50 ms electron beams through the EBIS trap has also been achieved. Gold spectra with a dominant charge state 34+ and total ion charge 55 nC measured on a current transformer have been obtained at the EBIS exit after a 30 ms confinement period. Recent studies with an in-line time-of-flight spectrometer with measurement of charge on a Faraday cup have shown 83% of the >28 nC extracted charge to be Au ions peaked at Au25+, for a 7 A electron beam and 10 ms confinement period. Typical normalized rms emittance values using a 6.8 A electron beam, 20–40 nC total ion charge, and 1–3 mA extracted ion current have been in the range of 0.08–0.1 π mm mrad. An energy analysis of the total extracted ion pulses >35 nC has indicated a longitudinal energy spread of <2 kV full width at half maximum after a 35 ms confinement period using a 7 A electron beam. Most design goals have been exceeded and much of the present work is geared toward improving reliability and providing larger safety margins. These include upgrading the electron gun, decoupling the electron beam launch energy from the electron collection energy, and tailoring the magnetic fields to reduce electron beam losses. Details of these measurements, tests in progress to improve performance, and plans for optimizing the design of the RHIC EBIS will be presented.

Extraction of highly charged Au ions from a multiampere electron beam EBIS at BNL

Excellent progress has been made in the operation of the Brookhaven National Laboratory electron beam ion source (EBIS), which is a prototype for an EBIS that could meet requirements for a RHIC preinjector. We have achieved very stable operation of the electron beam at 10 A through the EBIS trap. Ion injection of low charge gold ions from a low energy vacuum ion source [Brown et al., Rev. Sci. Instrum. 65, 1260 (1994)] and subsequent extraction of these ions with most probable charge state Au34+ has been demonstrated with electron beams up to 8 A. The total ion charge for gold measured on current transformer at the EBIS exit was 55 nC after a 30 ms confinement period. This corresponds to ∼85% of the theoretical ion trap capacity and exceeds our goal of 50% neutralization. The collected ion charge is proportional to the electron current and the gold charge state scales with the electron current density. Details of the EBIS configuration, total charge measurements, and time-of-flight spectra are given.