Room Temperature Electron Beam Ion Research Articles

Evidence of trielectronic recombination for Ar ions in an EBIT

SynopsisTrielectronic recombination has been investigated for Ar ions in a compact, room-temperature electron beam ion trap. A significant increase in hollow-core emission has been observed at the expected beam energy (~ 6.4 keV) for the KK→LMM resonance transition.

Cooling of highly charged ions—the HITRAP facility and Cooler trap

HITRAP is a facility at GSI in Darmstadt for decelerating, cooling and storing heavy, highly charged ions. It is designed to decelerate a beam of A/q < 3 particles with an energy of 4 MeV per nucleon as provided by the heavy ion storage ring ESR. HITRAP's decelerating linear accelerator (linac) will decelerate ions down to 6 keV per nucleon and then inject them into a Penning trap for cooling. The trap will capture bunches of up to 105 ions as heavy as U92+ in flight, cool and store them. After extraction from the cooler trap, the vertical beam line (VBL) transports the cold ions to the experiments. The linac has shown to decelerate ions down to 500 keV per nucleon on-line and to 6 keV per nucleon off-line. Recent tests with electrons and ions injected into the trap showed the necessity of a more careful electric and magnetic field alignment. An installed test ion source as well as a system of apertures and position sensitive diagnostics will be used to align the fields. A highly charged ion beam from a small room temperature electron beam ion trap was used for commissioning the VBL.

Demonstration of charge breeding in a compact room temperature electron beam ion trap

For the first time, a small room-temperature electron beam ion trap (EBIT), operated with permanent magnets, was successfully used for charge breeding experiments. The relatively low magnetic field of this EBIT does not contribute to the capture of the ions; single-charged ions are only caught by the space charge potential of the electron beam. An over-barrier injection method was used to fill the EBIT's electrostatic trap with externally produced, single-charged potassium ions. Charge states as high as K(19+) were reached after about a 3 s breeding time. The capture and breeding efficiencies up to 0.016(4)% for K(17+) have been measured.

Pyramidal pits created by single highly charged ions inBaF2single crystals

In various insulators, the impact of individual slow highly charged ions (eV-keV) creates surface nanostructures, whose size depends on the deposited potential energy. Here we report on the damage created on a cleaved ${\text{BaF}}_{2}$ (111) surface by irradiation with $4.5\ifmmode\times\else\texttimes\fi{}q\text{ }\text{keV}$ highly charged xenon ions from a room-temperature electron-beam ion trap. Up to charge states $q=36$, no surface topographic changes on the ${\text{BaF}}_{2}$ surface are observed by scanning force microscopy. The hidden stored damage, however, can be made visible using the technique of selective chemical etching. Each individual ion impact develops into a pyramidal etch pits, as can be concluded from a comparison of the areal density of observed etch pits with the applied ion fluence (typically ${10}^{8}\text{ }\text{ions}/{\text{cm}}^{2}$). The dimensional analysis of the measured pits reveals the significance of the deposited potential energy in the creation of lattice distortions/defects in ${\text{BaF}}_{2}$.

Investigations of the emittance and brightness of ion beams from an electron beam ion source of the Dresden EBIS type

We have characterized ion beams extracted from the Dresden EBIS-A, a compact room-temperature electron beam ion source (EBIS) with a permanent magnet system for electron beam compression, using a pepper-pot emittance meter. The EBIS-A is the precursor to the Dresden EBIS-SC in which the permanent magnets have been replaced by superconducting solenoids for the use of the source in high-ion-current applications such as heavy-ion cancer therapy. Beam emittance and brightness values were calculated from data sets acquired for a variety of source parameters, in leaky as well as pulsed ion extraction mode. With box shaped pulses of C(4+) ions at an energy of 39 keV root mean square emittances of 1-4 mm mrad and a brightness of 10 nA mm(-2) mrad(-2) were achieved. The results meet the expectations for high quality ion beams generated by an electron beam ion source.

A compact electron beam ion source with integrated Wien filter providing mass and charge state separated beams of highly charged ions

A Wien filter was designed for and tested with a room temperature electron beam ion source (EBIS). Xenon charge state spectra up to the charge state Xe46+ were resolved as well as the isotopes of krypton using apertures of different sizes. The complete setup consisting of an EBIS and a Wien filter has a length of less than 1 m substituting a complete classical beamline setup. The Wien filter is equipped with removable permanent magnets. Hence total beam current measurements are possible via simple removal of the permanent magnets. In dependence on the needs of resolution a weak (0.2 T) or a strong (0.5 T) magnets setup can be used. In this paper the principle of operation and the design of the Wien filter meeting the requirements of an EBIS are briefly discussed. The first ion beam extraction and separation experiments with a Dresden EBIS are presented.

Properties of the electron beam in a room-temperature electron beam ion source investigated by position sensitive x-ray detection

The evolution of the charge state distribution inside an electron beam ion source or trap (EBIS/T) is determined by interactions of the electron beam with the ions in the trap region. Hence, detailed information about the electron beam is required for evaluations of spectroscopic and ion extraction measurements performed at EBIS/T facilities. This article presents the results of investigations on the electron beam properties of an ion source of the Dresden EBIS type. For the first time theoretical predictions of the shape of the beam were tested for a noncryogenic EBIS working with low magnetic flux densities provided by permanent magnets. Position and width of the electron beam were measured at different electron energies showing an oscillation in the beam structure. At an energy of E(e)=16 keV and an emission current of I(e)=30 mA the beam is compressed to a radius of r(e)=57 mum (80% current). This refers to an average current density of j(e)=232 A/cm(2).

Production of highly charged argon ions from a room temperature electron beam ion trap**Supported by National Natural Science Foundation of China (10475035)

In this work, highly charged ions have been extracted from the advanced Electron Beam Ion Source (EBIS-A) developed in a scientific cooperation between the Dresden University of Technology and the DREEBIT GmbH Dresden. The charge state distributions of ions extracted from the EBIS-A are measured in the pulse and leaky modes under different operation conditions. Ar16+ ions with current of 2 pA are produced and extracted in the leaky mode. 3×105 Ar18+ ions per pulse are extracted in the pulse mode. The ion charge state distribution is a function of the ionization time.

Molecule fragmentation at the Dresden EBIS-A

We report on molecule fragmentation measurements of propane in high dense electron beams of a room-temperature electron beam ion source, the so-called Dresden EBIS-A. After fragmentation of propane molecules in the electron beam the fragments were continuously extracted and q/A separated by a bifocal dipole magnet. Fragmentation spectra were measured at working gas pressures of 10(-9) mbar up to 10(-8) mbar, electron currents of 29 mA up to 75 mA, and electron energies of 11 keV up to 15 keV. Thereby all possible stoichiometric ratios of propane fragments were detected. At low electron beam currents the ion current output of the CH(x)(+) (x=0-3) and the C(2)H(x)(+) (x=0-5) fragments is nearly identically. At higher electron currents the CH(x)(+) (x=0-3) peaks dominate the spectra and the ratio between the C(+) peak and CH(x)(+) (x=0-3) peaks increases from 2:1 to 3:1. It was shown that the working gas pressure has no significant influence on the fragment distribution but on the total ion current.

Production of a helium beam in a focused ion beam machine using an electron beam ion trap

Gallium liquid-metal ion sources that have been introduced in the late 1970s have allowed the development of a new class of micro- and nanofabrication tools collectively denominated as focused ion beam (FIB) machines. To investigate the potential of a helium beam in such a FIB instrument the authors have tested a room-temperature electron beam ion trap coupled with a high resolution FIB machine. In this letter they present their first results in target imaging using a helium beam with a resolution that allows to account for a beam diameter in the submicrometer range.

L x‐ray transitions in F‐like to Na‐like xenon ions determined at a room temperature electron beam ion trap

AbstractFluorine‐like to sodium‐like xenon ions were investigated by wavelength‐dispersive x‐ray spectrometry at the Dresden Electron Beam Ion Trap (EBIT) working at room temperature. In addition to the precise measurement of the L x‐ray transition energies following ionization, excitation and recombination processes in the highly charged xenon ions, the spectra were analyzed for different gas pressures in the trap. Multiconfiguration Dirac‐Fock calculations are introduced that were applied to the energies, transition probabilities and excitation cross‐sections. The production of neon‐like xenon ions was demonstrated even at very high gas pressures. Copyright © 2005 John Wiley &amp; Sons, Ltd.

A low energy ion beam line for highly charged ions

An ion beam line is presented, which is designed to study the interaction of highly charged ions with matter, especially solid surfaces. The highly charged ions are produced in a room temperature electron beam ion trap, the Dresden EBIT [1,2]. This device delivers bare nuclei up to elements with an atomic number of about 28, and neon-like ions up to about Z = 80 . After leaving the trap the ion beam containing several neighbouring ion charge states passes through standard ion optics elements before entering an analysing magnet for separating a certain ion charge state. In a following deceleration unit, which will be integrated soon, the ions can be slowed down to a definite kinetic energy of a few eV. The characteristic of the HCI beam is presented, combined with ion extraction spectra of selected elements detected by a Faraday cup after passing through an analysing magnet.

Dresden EBIT: Trap properties and ion production studied by X-ray spectroscopy of helium-like argon

The Dresden EBIT – a compact room-temperature electron beam ion trap (EBIT) – is able to produce argon ions in all stages of ionization. From measured argon X-ray spectra we determine electron beam current densities of 176–514 Acm−2 at measured electron beam diameters of 145 and 102 μm, respectively. Direct excitation processes in Ar16+ are studied in dependence of additional helium and neon admixtures acting here as coolant. It is shown that the addition of different light gases leads to a specific increase of some ten percent of the argon X-ray output from the trap.

Production of bare argon, manganese, iron and nickel nuclei in the Dresden EBIT

The production of highly charged argon, manganese, iron and nickel ions in a room-temperature electron beam ion trap (EBIT), the Dresden EBIT, has been investigated by means of energy dispersive X-ray spectroscopy of the direct excitation (DE) and radiative recombination (RR) processes. To derive the charge state distributions of the ions in the trap, direct excitation and radiative recombination cross-sections were calculated at electron energies of 8 and 14.4 keV. Based on these theoretical cross-sections and the measured X-ray spectra, the ion densities and the absolute number of ions, which are trapped in the electron beam, are determined for argon, manganese, iron and nickel. Emphasis has been paid to the highly charged ions, including the helium-like and hydrogen-like ions and bare nuclei. In the case of iron we also determined the contributions from lower ionization stages from DE transition lines. It is shown, that in the Dresden EBIT elements at least up to nickel can be fully ionized. Beside energy dispersive spectroscopy it is shown for iron by wavelength dispersive X-ray spectroscopy that with a comparably high gas pressure in the order of 10 −8 mbar carbon-, boron-, beryllium-, lithium- and helium-like iron ions can be produced.

The Dresden EBIT: An ion source for materials research and technological applications of low-energy highly charged ions

We report on a room temperature electron beam ion trap (DEBIT: Dresden EBIT). The construction of the DEBIT allows it to produce dense electron beams with current densities of at least 500 A cm −2 and an ionization factor of 5×10 21 cm −2 for electron beam energies up to 15 keV. Ions like Fe 26+, Kr 34+, Xe 49+ and Hg 70+ have been detected by X-ray spectrometry. The developed device has a high potential for investigations in nanomechanics, potential sputtering, information technology, ion beam lithography, etc., as it was demonstrated by different authors in studies utilizing a cryogenic EBIT or ECR ion sources. To enable adequate investigations a first compact ion extraction system for the DEBIT is described.

Highly charged metal ions produced from volatile organometallic compounds in a room temperature electron beam ion trap

A MIVOC system as it has been applied to several electron cyclotron resonance ion sources has been used to load a room temperature electron beam ion trap with a selection of different metals. X-ray measurements have demonstrated the ability of this method to produce highly charged ions for a large number of elements in a simple way and at low costs, which is favored by the low consumption rate of the used substances and operation of the ion trap at room temperature. The analysis of x-ray spectra measured with a Si(Li) semiconductor detector which is based on atomic structure calculations indicate the production of Mn23+, Fe25+, Ge30+, and Sn44+ ions.

A novel room temperature electron beam ion trap for atomic physics and materials research

Highly charged ions are used in basic investigations to study problems in atomic and plasma physics. Further on, the application of highly charged ions in materials research and other fields as nanomechanics and information techniques grew significantly in the last years. In the present paper, we report on results derived with a warm electron beam ion trap (WEBIT) that works without any cryogenic equipment. A special source construction allows to generate dense electron beams at room temperature with a current density of up to 240 A cm −2 and an acting ionization factor of (2⋯5)×10 21 cm −2 . Ions like Ar 17+, Xe 44+ and Ir 65+ were detected by X-ray spectroscopy. A charge capacity of about 8×10 7 elementary charges of the trap is estimated.