Seiji Tsurubuchi

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.

Landau-Zener model calculations of one-electron capture from He atoms by highly stripped ions at low energies

Cross sections for single electron capture from He atom by highly stripped, C q + , N q + , O q + , F q + , Ne q + ( q =4–9) and Kr q + ( q =10–25) ions have been calculated using the multichannel Landau-Zener model. The collision energy is 600 eV/amu except for Kr q + , whose energy is q ×1 keV. The selective electron capture into a single or at most two n -shells is predicted for the cases of q ≤9. The n -distributions obtained by the present calculation are quite consistent with our earlier observation and the total cross sections agree reasonably well with the measured data in spite of the simple model. In the case of Kr q + , where q is larger than 10, more and more shells can be populated and the total cross sections increase monotonically with the increase of q .

DISSOCIATIVE EXCITATION OF CH4 BY ELECTRON IMPACT : EMISSION CROSS SECTIONS FOR THE FRAGMENT SPECIES

Abstract Emission cross sections for the hydrogen Balmer series, Si lines and SiH band spectra appearing in the electron impact of SiH 4 were measured from the threshold to 1000 eVf. Fano-plot analysis shows that the optically forbidden states of SiH 4 play an important role in producing excited H atoms while the symmetrically allowed transitions are more important in the formation of excited SiH at high energies. A computer fitting to the intensity distribution of the experimentally obtained SiH band spectra was carried out to analyse the rotational and vibrational temperatures of SiH in the A 2 Δ state, which was produced by a single collision between an electron and an SiH 4 molecule.

Absolute Measurements of Emission Cross-Sections for Dissociative Excitations of H2O by Electron-Impact with Crossed-Beam Apparatus and High Sensitive Quartz Spring Balance

Absolute measurements of the emission cross-sections for the A - X band-spectrum of OH and the H β line in the dissociative excitation processes of H 2 O by electron-impact have been carried out by means of the crossed-beam technique, with the aid of a high sensitive spring balance made of fused quartz. The spring has a tiny pan, which is surrounded by a specially designed trap of liquid nitrogen. The spring words well for direct intensity measurements of the water molecular beam, because the condensation coefficient of H 2 O on ice is large enough at lower temperatures. The following results have been obtained; (4.2±2.1)×10 -18 cm 2 for the H β transition, and (7.1±3.5)×10 -18 cm 2 for the OH ( A , 2 Σ + - X , \(^{2}\varPi\)) transition, at 300 eV respectively.

Comparison between Crossed-Beam and Target-Gas Methods for Study on Optical Excitation Functions in Electron-Impact of H2O

The so-called “crossed-beam method” and “target-gas method” are applied to the same events of molecular collisions. It is shown that the former method gives reliable informations about the excitation functions for the OH band and the Balmer lines in dissociative and radiative collisions of H 2 O with electrons, while the latter does not, at least, in the range of lower energies of incident electrons.

Optical Oscillator Strengths of the Resonance Lines of Rare Gases

Optical oscillator strenths of the resonance lines of Ne, Ar, and Kr atoms were measured by the method of the self-absorption. The results obtained are Ne: 2 p 6 1 S 0 -3 s ′ [1/2] o (735.9 A), f =0.123±0.006 Ne: 2 p 6 1 S 0 -3 s [3/2] o (743.7 A), f =0.0122±0.0006 Ar: 3 p 6 1 S 0 -4 s ′ [1/2] o (1048.2 A), f =0.213±0.011 Ar: 3 p 6 1 S 0 -4 s [3/2] o (1066.7 A), f =0.057±0.003 Kr: 4 p 6 1 S 0 -5 s ′ [1/2] o (1164.9 A), f =0.139±0.010 Kr: 4 p 6 1 S 0 -5 s [3/2] o (1235.8 A), f =0.155±0.011.