Study of the Electron-Capture Phenomena in the Electron-Cooling Process of Highly-Charged Ions

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For the electron-cooling process, ions merge with electrons at a part of the long straight sections of the storage-ring circumference. In this case, ions capture the cooling electrons at a certain probability. The particles which changed their charges in this way deviate from the main orbit of the ring and so it is easy to detect them. Such a charge-changed beam includes much important informations on electron and ion beams. Therefore, one can diagnose the accelerator by the detailed analysis of the charge-changed beam measurement.On the other hand, the electron-cooling section is the field where ions with good qualities interact with the electrons having relative velocities ranging from zero to a large value. In this sense, the cooling electrons can be regarded as a pure high-density electron target. The ion-electron interaction which is an important branch of atomic physics research can thus be studied by using these devices.Research was performed for three kinds of ions : 1) The ele … More ctron capture process of H^+ beam has well been known experimentally and also theoretically. Taking advantage of this fact, we studied the electron cooling process by observing the neutral hydrogen atoms created through electron-capture. From the capture rate, we could deduce the electron temperature as 0.2 eV. On the other hand, from the measurement of the neutral beam 「rofile, the emittance of the circulating cooled-beam was found to be 1-2 pi mmmrad. Furthermore, for the bunched beam, the bunch width was estimated by the measurement of the distribution of the arrival times of neutral atoms at the detector. The width was a few ten nsec, which contrast to the initial width of a few hundreds nsec. 2) For the electron capture studies on H_2 ^+ ion. a pair of hydrogen atoms were observed, which come from the dissociative recombination process H_2 ^++e--H+H. From the detailed analysis, the intersection angle between electron and ion beams was estimated. 3) For the studies on the electron capture of ^3He ^+ ion, the dielectronic recombination process was first observed. It is the process in which already attached electron in ^3He ^+ is also excited from 1s to 2p state at the save time that a ferr electron is captured. The result is consistent with a theoretical prediction. In future, we wish to extend these studies to heavier ions. Less