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Charge State Distribution of Highly Charged Ions Passing through Microcapillaries
| Content Provider | Semantic Scholar |
|---|---|
| Author | Dumitriu, Daniela Kanai, Yasuyuki Iwai, Yoshiki Morishita, Yasuo Oyama, Hitoshi Yamazaki, Yasunori |
| Copyright Year | 2000 |
| Abstract | The formation mechanism and the properties of hollow atoms have been intensively studied by many groups. To study the intrinsic nature of hollow atoms in the first generationhollow atom above the surface(HAA)-is difficult in typical ion-surface experiments, because the time interval between the HAA formation and its arrival at the surface is shorter than its intrinsic lifetime. A new and powerful method known as Beam Capillary Spectroscopy (BCS) has been recently developed 3,4) allowing their direct observation in vacuum by using a thin microcapillary as a target. We have measured the charge state distribution f(qf) of the ion transmitted through a Ni microcapillary target as a function of the final charge state qf in order to study the formation mechanism and the properties of HAA. 22 keV O and N ions (q =5,6,7) from a 14.5 GHz ECR ion source at RIKEN were used as incident projectiles. The charge state of the ion transmitted through the target was analyzed by a new charge state analyzer built in Atomic Physics Lab. It consists of two sets of deflectors combined with a ceratron. The deflectors are arranged in a "cascade" type configuration, the beam being deflected on vertical direction in his passing from one deflector towards another, until it reaches the ceratron. The first deflector consists of planar electrodes inclined at 15° with respect to the beam direction. The second one is a 128° cylindrical sector type. One of the electrodes for each deflector is grounded. As high voltages up to 20kV can be applied on both deflectors, the analyzer can in principle separate rather high charge states (13+ from 14+) for incident energies in the range of few hundreds keV. The ceratron is located very close to the exit of the second deflector. The negative voltage is applied to a mesh, which is located in front of the ceratron, to prevent possible stray electrons entering the ceratron. A movable Faraday cup located between deflectors is used for adjusting the beam. The Ni microcapillary target (area: 4mm, length : 3.8 μm) is set in front of the analyzer. The pressure of the target region is approx. 2x10 torr. The beam is collimated by a 5 mm aperture, which is located at 1m from the target, and a 2x2 mm aperture cerated by a four jaw slits system. Results are shown in Fig. 1. One can see in Fig. 1 the following features: (1) One electron capture fraction( qf = q-1) is the predominant in the charge changed fractions, independent of the projectile and initial charge state. (2) Almost neutralized projectiles (q=1) are produced in large quantities and comparable to that for one electron capture. (3) The other charge states fractions ( 1< qf < q-1) are lower than those for qf =1 and qf =q-1. (4) For the same initial charge state q, almost similar behavior was found in the final charge state distributions. |
| Starting Page | 64 |
| Ending Page | 65 |
| Page Count | 2 |
| File Format | PDF HTM / HTML |
| Volume Number | 26 |
| Alternate Webpage(s) | http://www.riken.jp/ap/publication/files/Dana_coll-rep26.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
