J. Plasma Fusion Res. SERIES, Vol.7 (2006) 323-326

Production and Compilation of Charge Changing Cross Sectionsof Ion-Atom and Ion-Molecule Collisions
IMAI Makoto, SHIRAI Toshizo1∗ , SAITO Manabu2 , HARUYAMA Yoichi2 , ITOH Akio3 , IMANISHI Nobutsugu# ,FUKUZAWA Fumio# and KUBO Hirotaka1
Department of Nuclear Engineering, Kyoto University, Kyoto 606-8501, Japan
1 Japan Atomic Energy Research Institute (JAERI), Ibaraki 311-0193, Japan
2 Kyoto Prefectural University, Kyoto 606-0823, Japan
3 Quantum Science and Engineering Center, Kyoto University, Kyoto 611-0011, Japan（Received: 4 October 2004 / Accepted: 27 August 2005）

Abstract
Single electron capture cross sections σ10 , σ21 for singly and doubly ionized ions and double electron
capture cross sections σ20 for doubly ionized ions of Be, B, Fe and Ni with atomic and molecular gas targets
are derived experimentally in the energy range of 0.5 − 32 keV. The current status of our compilation ofexperimental cross sections for charge changing collisions is also presented.
Keywords:
electron capture, charge exchange, cross section, beryllium, boron, iron, nickel, collisional database
1．Introduction
Charge changing processes of ions for high-Z materials including stainless consisting elements as well as
low-Z materials such as Be and B are of practical importance for controlled thermonuclear fusion research.
Upon this point of view, we have been cooperating
in production and compilation of experimental chargechanging cross sections for ion-atom and ion-molecule
collisions since 1983, as a part of data center activities
of JAERI [1].
We have measured single and double electron capture cross sections for Cq+ (q = 1 − 4) ions with H2 ,CH4 , C2 H6 , C3 H8 and CO2 molecules in the collisionenergy range of (1 − 20)q keV [2], and now devoted tothe single and double electron capture cross sections,
σ10 , σ21 and σ20 , and even the electron loss cross sections σ12 for Be, B, Cr, Fe and Ni ions colliding with
He, Ne, Ar, Kr, H2 , CO, CO2 , CH4 , C2 H6 , C3 H8 , CO,
CO2 and N2 atoms and molecules at collision energies
of 0.5−32 keV. In this paper, results for electron capture
cross sections for Be, B, Fe and Ni ions are presented
with the current status of the data compilation.

Fig. 1 The experimental setup.

Impact-Ion-Source [3], in which a pump beam of 0.8
MeV CO2 + impacts a metal wire. For production ofBe, Fe and Ni ions, pure metallic wires of ≥ 99.9 %purity were set in the ion-source, while a wire of Fe,
B and Si alloy was used for B ion. A combination ofa Wien-filter and an electric field for removing neutrals (Neutral Particle Rejecter; NPR) selects the incident ion by its charge state. Another role of the NPR
is to remove the backscattered fragments of the pumpbeam, because the charged fragments at equal velocity
can pass the Wien Filter. The selected ion beam collides
with the target gas, filled in a gas cell, whose pressure
was monitored with a high-sensitivity-Pirani gauge calibrated with a capacitance manometer (MKS Baratron).
Outgoing ions were electrostatically separated and de-2．Experiment
The experiment has been performed using the Vande Graaﬀ Accelerator Facility of the Quantum Scienceand Engineering Center, Kyoto University. As is illustrated in Fig.1, incident ions were obtained by Ion-C 2006 by The Japan Society of Plasma

Corresponding author’s e-mail: imai@nucleng.kyoto-u.ac.jp* Deceased in 2002
# Retired from Kyoto University

Science and Nuclear Fusion Research323

Production and Compilation of Charge Changing Cross Sections of Ion-Atom and Ion-Molecule Collisions

tected with position sensitive detector utilizing a micro channel plate (MCP-PSD). All the charge-separated
ions and neutrals were detected with a single MCP sothat the detection eﬃciencies cancel each other on deriving the charge fractions. Signals from MCP-PSD
were recorded event by event to confirm that the detection eﬃciencies for each charge fraction do not differ under diﬀerent counting rates by reproducing thepulse height distributions for each detector position.
Cross sections were derived by a growth method undersingle collision condition with gas target pressures of
10−2 − 10−1 Pa, while the base pressure of the vacuum
chamber was kept below 8 × 10−8 Torr. To guarantee
the blow out of the target gas from both ends of the gas
cell, we included the half diameter of the entrance andexit apertures (0.5 and 4.0 mm, respectively) to the gas
cell length (45.0 mm). The validity of this calibration
had been confirmed by measuring H+ + H2 → H single capture cross section with the present apparatus at
7.5 keV. The total uncertainties are estimated to be 9-20%, which mainly come from the eﬀect of residual gases
and the uncertainty of Pirani gauge reading.

in the impact-ion-source. Our preliminary result for single electron capture cross section of Cr+ indicates thatthe metastable fractions may give rise to the electron
capture by a factor of 10 or so. It is also demonstratedin the Fig. 3 that the cross sections for double electroncapture σ20 to form the neutral atom are larger than orcomparable to those for single electron capture σ10 for
Ni ions in the energy range investigated. For better understanding the electron capture collisions of transition
metal ions, further studies are required both in experimentally and theoretically.
4．Data compilation
We have been compiling experimental total crosssection data for electron capture or loss since 1983, andpartial cross section data since 1992, published in journals of our selection. Experimental cross sections forsome related interactions, like inner-shell ionization oftarget, ion-ion collisions, cluster collisions and so on,
are also under the compilation since 1995. This compilation has been done not specifying the projectile ion or
target of the collision system, taking its aim at a larger
area of applications as well as fusion research. All thecompiled data after 1989 are stored numerically, including the case that only a figure is published. An electrical version of this compilation is under the development
now, utilizing Oracle database management system. We
have defined the database structure, which consisted of
8 tables. The collected papers are indexed by document number key docno and the data are indexed by
a combination of document and system number keys
docno, sysno”, for cases that single paper includes
multiple collision systems. The most important tables
are the ones called COL, DATA and DOC, which store
collision system information, numeric data and bibliographic indexes, respectively. In case that cross section data for some collision system are required, docno,
sysno keys for the desired system are looked up in thetable COL and the numeric data are derived from the table DATA using those docno, sysno keys. If the bibliographic information is additionally required, it can belooked up in the DOC table with docno” key. Reference with specifying the known paper’s information is
also possible by looking the docno key up in the table
DOC and look into COL and DATA tables. We intend
to open this electrical version to the public through webbrowsers, and to make it possible for other database systems to make an SQL query through provided accountand password by opening the database specifications.

3．Experimental results
The measured cross sections are presented in Figs.
2 and 3 for low-Z (Be, B) and high-Z (Fe, Ni) projectile ions, respectively, with theoretical results for
Beq+ (q = 1, 2) + He collision systems by Shimakura(σ10 ) [4], Fritsch (σ21,20 ) [5] and Suzuki et al. (σ21 )[6], σ21 for Be2+ + H2 collision system by Kimura andLane [7] and Schultz et al. [8], and σ10 for B+ + He collision system by Shimakura et al. [9] and Hansen andDubois [10]. As for high-Z ions, no data has been published for the present collision systems in this energy
range except for the experimental measurement of σ10
for Fe+ + Ar, N2 collisions by Layton et al. [11], which
covers the higher continuous energy region. In the Fig.
2(a), the calculations of Shimakura [4] and Fritsch [5]for the single electron capture cross sections σ10 andσ21 , respectively, for He target are found to have an excellent agreement with the present experiment. Also
the calculation of Kimura and Lane [7] for H2 target
shows an excellent agreement with the present experiment in the Fig. 2 (a’). The calculation of Schultz
et al. [8] was derived by classical trajectory Monte
Carlo (CTMC) method and has no calculation point in
the present energy range, but its interpolation coincides
very well with our measurement. The present cross sections for Fe+ + Ar, N2 collisions fairly well connect theexperimental results by Layton et al. [11], although thepresent values are found to be a little higher, which may
come from the metastable fractions of Fe+ ion produced

5．Acknowkedgement
The authors thank their students at Kyoto Univer324

Production and Compilation of Charge Changing Cross Sections of Ion-Atom and Ion-Molecule Collisions

Fig. 2 Single and double electron capture cross sections σ10 , σ21 and σ20 for (a), (a’) Be ions and (b), (b’) B ions. In the (a)and (b) quadrants, circles, down triangles, squares and diamonds denote He, Ne, Ar and Kr targets, respectively,
while circles, down triangles, squares, diamonds, up triangles and hexes denote H2 , CH4 , C2 H6 , C3 H8 , CO andCO2 targets, respectively, in the (a’) and (b’) quadrants. Present value: symbols connected with full and dashedlines, σ10 and σ21 , respectively; small symbols connected with dotted lines, σ20 . Theories: (a) full line, σ10 for Heby Shimakura [4]; long and short dashed line, σ21 for He by Fritsch [5] and Suzuki et al. [6], respectively; dottedline, σ20 for He by Fritsch [5]; (a’) full and dashed line, σ21 for H2 by Kimura and Lane [7] and Schultz et al. [8],respectively; (b) full and dashed line, σ10 for He by Shimakura et al. [9] and Hansen and Dubois [10], respectively.

Fig. 3 Single and double electron capture cross sections σ10 , σ21 and σ20 for (a), (a’) Fe+ ion, (b1), (b1’) Ni+ ion and(b2), (b2’) Ni2+ ion. In the (a), (b1) and (b2) sections, circles, squares and diamonds denote He, Ar and Kr targets,
respectively, while dark circles, down triangles, squares, diamonds, up triangles, hexes and pale circles denote
H2 , CH4 , C2 H6 , C3 H8 , CO, CO2 and N2 targets, respectively, in the (a’), (b1’) and (b2’) sections. Present value:symbols connected with full and dashed lines, σ10 and σ21 , respectively; small symbols connected with dotted lines,
σ20 . Smaller square and circle with full line in the (a) and (a’) sections denote experimental values σ10 for Ar andN2 targets, respectively, by Layton et al. [11]325

Production and Compilation of Charge Changing Cross Sections of Ion-Atom and Ion-Molecule Collisions

sity for their contributions to this study. H. Kageyama,K. Yamada, K. Yoshimoto, K. Ikeda, T. Kuhara, Y.
Okamoto, T. Kadono and S. Sugisaki are specificallyappreciated. M. I. is supported partly in this study by aGrant in Aid for Scientific Research from the Ministryof Education, Culture, Sports, Science and Technologyof Japan. This work was supported in part by Japan
Atomic Energy Research Institute (JAERI).

[1]
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N. Shimakura, private communication.
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S. Suzuki, L. Gulyás, N. Shimakura, P.D.
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(2000).
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410 (2001).
[10] J.P. Hansen and A. Dubois, Physica Scripta T62,
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Comeaux, G.D. Magnuson and P. Mahadevan,
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