Volume 71, Issue 2, February 2000
Index of content:
- ECR ION SOURCES (I)
71(2000); http://dx.doi.org/10.1063/1.1150342View Description Hide Description
Short life radioactive beams presently need charge breeders either for continuous or pulsed postaccelerators. Until recently these charge breeders were mainly based on stripper foils and or electron beamion source projects associated with ion trap bunching devices. In 1995 however, we demonstrated the feasibility of radioactive electron cyclotron resonanceion source (ECRIS) charge breeders with rather good efficiencies working in continuous regime and well adapted for continuous postaccelerators. In 1998, we demonstrated also the feasibility of pulsed ECR ion traps (ECRITs) which are well adapted for pulsed postaccelerators with short life radioactive ion bunches. In this article, we explain the basic principles of these devices shortly named ECR systems and compare their characteristics with other systems. More precise results are given in companion articles at this meeting.
71(2000); http://dx.doi.org/10.1063/1.1150331View Description Hide Description
Initially developed for radioactive ion beam production, the electron cyclotron resource (ECR) charge breeder shows that the beam injection of a primary beam inside an ECR ion source is a very general process for beam production. In this article we will review the latest results obtained on the ISN Grenoble test bench for the production of clockwise (CW) or pulsed metallic ion beams with the so-called method. New results are given for CW operation where the efficiency is particularly optimized for application to multicharged radioactive ion production (for example, 3.5% for 4.2% for 5% for Different ion sources have been used to study the variation of the efficiency as a function of the energy of the 1+ primary beam.Charge state distributions are especially measured for Pb and Rb ions. A new mode of operation, the electron cyclotron resonanceion trap breeder/buncher, which permits the trapping and the bunching of the ion beam is demonstrated and experimentally verified. The injection of a ion beam leads to a 11.5 μAe peak current of the ion beam extracted during the first ms. The temporal evolution of the cumulated particle transformation and trapping efficiency is measured in the case of This new method shows that it is possible to modify the time structure of the injected beam, just by trapping the ions inside the plasma and re-extracting them by using the “afterglow pulsed mode.” It will also be shown that it is possible to produce “multi-charged metallic ions” by using a primary source for the dissociation of a complex molecule and then by injecting the low charge state beam inside the multicharged electron cyclotron resonanceion source. A preliminary example will be presented for the production of by injection of obtained from dissociation of gas.
71(2000); http://dx.doi.org/10.1063/1.1150332View Description Hide Description
We have tried to shed more light on the possible mechanisms of the beneficial effect of gas mixing for highly charged ion production, in particular on the presence of an ion cooling effect. For the first time a method was applied to deduct the ion temperature from all measured ionic currents. The ion temperature values derived showed a clear decreasing trend in conjunction with mass changes of the gas mixture, consisting of “pure” argon (no mixing gas), argon plus natural oxygen, argon plus isotopic or argon plus Each of the applied mixing gases gives a higher charged ion (HCI) output (highest for as well as a lower ion current for the singly charged beam-particle output. The relative high particle fraction (about 40%) of singly charged nonbeam particles is an indication that effective plasmaion cooling is possible. Although the differences in ion temperature calculated are small, the effect is likely substantial, since the ion confinement has a dependency with Hydrogen currents (residual) are observed to be smallest for the best HCI-confined plasmas; so far no explanation for this can be given.