Kenji Motohashi

A New Versatile Electron-Beam Ion Trap

We have constructed an electron-beam ion trap (EBIT) to facilitate the creation and study of highly charged ions. After a brief introduction to EBITs in general, we describe the design of the new device, highlighting its unique features. Some preliminary results are presented which demonstrate the devices capability to produce and study highly charged ions.

Characteristics of the Tokyo Electron-Beam Ion Trap.

We have constructed a new Electron Beam Ion Trap (EBIT). Over recent months, we have operated this device and obtained some experimental results. In this paper, we show the performance of this EBIT by illustrating these results.

Compact electron-beam ion trap using NdFeB permanent magnets

A compact electron-beam ion trap (EBIT) as a multiply charged ion source for medium Z, e.g., Ne10+, Ar18+, Kr26+, and so on, has been developed. A pair of NdFeB permanent magnets generates an intense magnetic field (0.64 T) along with the electron-beam axis. The maximum electron-beam energy and current were designed as 10 keV and 30 mA, respectively. Over 95% of the electron beam up to 20 mA was transmitted to an electron collector. All parts, including electrical feedthroughs, are mounted on a con-flat flange with an 8 in. diam. Portability is added to the EBIT because no cooling system for the electromagnet is needed. Hydrogen-like Ar17+ were extracted.

An overview of the Tokyo electron beam ion trap

A new Electron Beam Ion Trap has recently been completed in Tokyo. The general features of the apparatus, design and operation are given. This paper also surveys the planned and ongoing experimental program.

Electron-impact emission cross sections of Ar

Electron impact emission cross sections of Ar were measured for the , and transitions from the threshold to 1000 eV by a polarization-free method. Two different methods were used in determining absolute emission cross sections for the first resonance lines. The first method is to measure the cascade cross sections to the 4s state by detecting visible to near-infrared radiation and the total cascade cross section was then combined with the level excitation cross section to the 4s state to give the emission cross section for the resonance line. The second method is to measure the vacuum ultraviolet sensitivity of the apparatus and an absolute emission cross section for the resonance line was obtained by comparing its spectral intensity with that of the Lyman- radiation produced from by electron impact. The two results showed good agreement within the experimental errors. The level excitation cross sections to the and states were obtained by subtracting the total cascade cross section to these levels from the corresponding emission cross sections.

The present status of the Tokyo electron beam ion trap

Recent progress of the Tokyo electron beam ion trap (Tokyo-EBIT) project is described. The Tokyo-EBIT is of an original design and construction with several features different from other EBITs in the world. The maximum energy and current of the electron beam are designed to be 340 keV and 300 mA with a magnetic field of 4.5 T. The ongoing and planned physics experiments are described and the results for the initial stage of operation of the Tokyo-EBIT are given.

3D-momentum-imaging spectroscopy of fragment ions produced in electron transfer collisions between energy-gain selected Arq+ (q = 3, 8, 9, 11 and 12) and CF4 molecules

The energy gain of Ar(q−1)+* scattered at small angle (< 0.29 mrad) and three-dimensional momenta of fragment ions were measured in coincidence in electron transfer collisions between Arq+ (q = 3, 8, 9, 11 and 12) and CF4. The experiments were carried out under the condition that the energy gain becomes approximately equal to the heat of reaction for the intermediate collision system produced just after the electron transfer process. Main components due to single-electron transfer as well as sub-components due to transfer ionization of double-, triple- and quadruple-electron transfer processes were clearly observed in the energy-gain spectra. The position and height of the energy-gain spectra were in good agreement with the theoretical ones calculated by the classical over-the-barrier model. The shapes of time-of-flight mass spectra of fragment ions were drastically changed between single-and double-electron transfer (transfer ionization). 3D momenta of F+, CF+, CF2+, CF3+, CF22+ and CF32+ were measured with a new spectroscopic device, as well as the energy gain of Ar(q−1)+*. Both electronic states of Ar(q−n)+* and CF4n+* (n = 1 and 2) produced just after the electron transfer were assigned experimentally by taking into account the released kinetic energy which was converted from the 3D momenta of fragment ions and the heat of reaction.

Detector systems for use with an electron beam ion trap

This article describes two data systems, primarily for use with x-ray detectors in conjunction with an Electron Beam Ion Trap (EBIT). Both systems are designed from a common viewpoint that useful information should be presented in real-time whilst as much information as possible should be stored for subsequent off-line analysis.

X-ray spectroscopy at the Tokyo electron beam ion trap

We have observed x-ray signals from He-like Ba and Ne-like W ions trapped in an Electron Beam Ion Trap (EBIT) at an electron beam energy of 19.9 keV. In the spectra, several transitions in Ne-like Ba and W ions and radiative recombination processes (RR) to n ≥ 2 levels were observed. These atoms were seeded by the cathode and were ionized in the trap region by electron impact. We have observed dielectronic recombination processes (DR) in Ne-like Xe.

Estimation of Emission Cross Section for CH+(A 1 Π-X 1 Σ+: 419.0–441.0 nm) Produced by Electron Impact of CH 4 Using Spectral Simulation Technique

Emission cross sections for CH + (A 1 Π-X 1 Σ + ) produced by single electron impact of CH 4 are estimated at 100 and 400 eV by subtracting the calculated band intensities for CH(A 2 Δ-X 2 Π) from the experimentally measured band spectra. Vibrational and rotational temperatures are analyzed for CH molecule in the A 2 Δ state by fitting calculated band intensities assuming the Boltzman distributions in the upper electronic state to experimental ones at 17, 28, 100 and 400 eV. Rotational population distribution at 17 eV is quite different from others.