摘要:

High charge states of heavy ions inside the electron cyclotron resonance plasma are produced by hot and warm electrons with energies above 3 keV. The slope of the electron energy distribution function and the density of these populations were obtained from bremsstrahlung spectra emitted by the 7.5 GHz Electron Cyclotron Resonance Ion Source of the Forschungszentrum Rossendorf measured with a HP Ge solid state detector. For this a new deconvolution method has been used. The operating condition of the ion source influences the behavior of the electrons. Mixing in of light gases to the discharge strongly increases the electron density. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146707

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The experiments described here were performed at a 5 GHz electron‐cyclotron‐resonance ion source with a magnetic hexapole. The discharge was run in argon. By launching a fast magnetoacoustic wave from the high‐field side (end on) we heated hydrogen ions—present in traces from the residual gas—at their fundamental ion cyclotron resonance (ICR) frequency of 2.2 MHz with 5 W only. As a consequence the currents of Arq+ions extracted from the source were significantly increased forq≥5 while the currents of lower charged argon ions were decreased, indicating an enhanced plasma confinement. However, a reduction of the hydrogen content in the residual gas resulted in a reversal of the effect of ICR heating. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146708

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A pulsed 14 GHz ECR4 source, adapted to operate in the afterglow mode, was delivered by GANIL to CERN in the framework of the Heavy Ion Facility Project. After four months of operation to commission the facility, it completed its first operational run of nine weeks at the end of 1994, providing lead ions to nuclear physics and ion cooling experiments. A very stable beam, with a useful length of over 1 ms, of 80e&mgr;A of Pb27+was provided by the source over this period. The operational problems experienced during the commissioning and operation, and the investigations to improve performance for the next experimental physics run are presented. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146709

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The pulsed magnetic field (PuMa)‐electron cyclotron resonance (ECR) ion source uses a pulsed coil to improve the peak current by opening the magnetic bottle along the beam axis. After demonstration of the principle of the pulsed magnetic extraction, the ion source was tested with different gases. We received promising results from helium to krypton. The influence of the current in the pulsed coil on the analyzed ion current was measured. With increased current levels within the pulsed coil not only the pulse height of the PuMa pulse, but the pulse length can also be controlled. By using the pulsed coil the maximum of the charge state distribution can be shifted to higher charge states. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146710

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

During the afterglow of the pulsed electron cyclotron resonance discharge, currents can be extracted, which are substantially higher than the ion current during the heating phase of the plasma. This is especially the case for the high charge states of heavy ions. An operating regime was found, which gives an extremely stable and reproducible afterglow. The variation from pulse to pulse is hardly visible and the long‐term stability is also very good. This mode, which made the setting up and operation of the accelerators much easier than is normally the case, can also give an insight into the processes responsible for the afterglow. An investigation of the shape and duration of the afterglow for the different charge states of lead is presented. A 1/&zgr;2dependence for the decay time of the afterglow was found for operation with oxygen, while no such dependence appears for operation with neon as the auxiliary gas. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146711

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

At CERN there is a demand for high currents of highly charged ions, presently for fixed target experiments at the SPS and in the future for the LHC project. The LHC, however, requires an intensity, which is an order of magnitude larger than the intensity presently achieved using an electron cyclotron resonance ion source. Laser ion sources have the potential to fulfill the LHC requirements, although a large number of technical problems have to be overcome. At CERN a project to investigate the feasibility of the application of laser ion sources was started in 1989 and a source capable of producing large currents of highly charged ions was constructed. The results of the investigations on this source, including charge state distributions, measurements of the energy distribution, measurements of ion currents, and emittance measurements will be presented. Furthermore a method to reduce the time‐dependent energy change is described. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146712

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The feasibility of laser‐induced photoemission as a driving mechanism for short plasma pulse production is currently being investigated with a pulsed excimer laser at 248 nm. Low work function materials such as LaB6and barium are used as cathode materials and the resulting plasma characteristics are being examined. Results from early measurements of the barium photocathode show a strong dependence of the photoemitted current on the source pressure and cathode voltage. Additionally, the temporal behavior of the emitted electron pulse is found to consist of two components: a short 50 ns burst corresponding to laser‐induced photoemission, and a larger, longer 100 ns pulse increasing from the tail end of the photoemitted electron pulse. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1147244

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The main statements of the new Joint Institute for Nuclear Research (JINR) research and development (R&D) project ‘‘Investigations on the Physics of Multicharged Ion Sources for JINR and CERN Hadron Accelerators’’ are presented in this report. The project will be performed with the purpose of improving the source efficiency for the JINR and CERN accelerator complexes. The project will include the theoretical and experimental investigations as well as x‐ray spectroscopy of highly charged ion plasma in the sources. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146659

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The microwave plasma cathodes (MPC) dedicated to high‐current ion sources are characterized by long lifetime with reactive gases and a compact structure. An Ishikawa‐type MPC developed at GSI Darmstadt coupled with the CHORDIS ion source is presented. The electron current of the MPC is extracted from a dense plasma generated under electron‐cyclotron‐resonance condition. The axial magnetic field is produced by permanent magnets and ferromagnetic components. The 2.45 GHz microwave power (some tens of watts) is introduced into the plasma chamber via a coaxial line ended with a helical antenna. Experiments with argon and oxygen gas are presented and discussed. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146660

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Two single‐stage, 6 GHz electron cyclotron resonance (ECR) ion sources are currently in use at the ARENAS project at Louvain‐la‐Neuve. One of them is used to ionize radioactive elements to low charge states (1+to 4+) before injection in the postaccelerator cyclotron. High intensity beams of6He,11C,13N,18Ne, and19Ne are being produced. Recently the source has been adapted for the ionization of18F and the first experiment with this beam has been performed. A second ECR source, almost identical to the first, is used in combination with the Leuven isotope separator on‐line. It produces stable and radioactive beams at 50*qkeV. Mass separated beams of13N,14O, and15O can be produced using a high‐temperature carbon target. An upgrade of this type of ECR source is now under construction. It consists mainly of increased magnetic fields and the capability for insertion of a heated cavity. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146661

出版商:AIP    

年代:1996

数据来源: AIP