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  • 1
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The large number of different experiments performed at the 88 Inch Cyclotron requires great variety and flexibility in the production of ion beams. This flexibility is provided by the two high performance electron cyclotron resonance (ECR) ion sources, the LBL ECR and the AECR-U, which can produce beams of ions as light as hydrogen and as heavy as uranium. With these two sources, up to six different metals can be preloaded using two types of ovens. The ovens are mounted radially on the ion sources and inject the metal vapor though the open sextupole structure into the plasma chamber. For the superconducting ECR ion source VENUS, which is under construction at Lawrence Berkely National Laboratory, the use of radial ovens is no longer possible, because the magnetic structure is closed radially. Therefore, we are developing two new axial oven types for low and high temperature applications. Metal ion beam production in ECR ion sources using the oven technique is discussed. The design of the axial oven is presented. Finally, the efficiency of the axial oven is compared with the radial oven for the production of Ca. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2947-2952 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The mean plasma potential was measured on the LBL advanced electron cyclotron resonance (AECR) ion source for a variety of conditions. The mean potentials for plasmas of oxygen, argon, and argon mixed with oxygen in the AECR were determined. These plasma potentials are positive with respect to the plasma chamber wall and are on the order of tens of volts. Electrons injected into the plasma by an electron gun or from an aluminum oxide wall coating with a very high secondary electron emission reduce the plasma potential as does gas mixing. A lower plasma potential in the AECR source coincides with enhanced production of high charged state ions indicating longer ion confinement times. The effect of the extra electrons from external injection or wall coatings is to lower the average plasma potential and to increase the neτi of the ECR plasma. With sufficient extra electrons, the need for gas mixing can be eliminated or reduced to a lower level, so the source can operate at lower neutral pressures. A reduction of the neutral pressure decreases charge exchange between ions and neutrals and enhances the production of high charge state ions. An aluminum oxide coating results in the lowest plasma potential among the three methods discussed and the best source performance.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 221-224 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Electron cyclotron resonance ion sources (ECRIS) using rf between 5 and 16 GHz have been developed into stable, reliable sources of highly charged ions produced from a wide range of elements. These devices are currently used as ion sources for cyclotrons, synchrotrons, and heavy-ion linacs for nuclear and relativistic heavy-ion physics. They also serve the atomic physics community as a source of low energy multiply charged ions. In order to improve their performance both with respect to maximum charge state and beam intensity, ECRIS builders are now designing and constructing sources which will operate at frequencies up to 30 GHz. In this article we review the present status of operating ECRIS, review recent experimental measurements on plasma parameters, and look at the technology and potential of sources operating at frequencies up to 30 GHz.
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  • 4
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The next-generation, very high magnetic-field electron cyclotron resonance (ECR) ion sources, like VENUS, SERSE, or PHOENIX, strive for substantially (a factor of 10) higher extracted heavy ion beam intensities than currently achievable. Such high-intensity ion beams present significant challenges for the design and simulation of an ECR extraction and low-energy ion beam transport system. Extraction and beam formation take place in a strong (up to 3 T) axial magnetic field, which leads to significantly different focusing properties for the different ion masses and charge states of the extracted beam. Typically, beam simulations must take into account the contributions of up to 50 different charge states and ion masses. Space charge effects must be correctly included since the extraction and mass analyzing system have to be designed for a proton-equivalent current of ∼25 mA at 30 kV extraction voltage. The article discusses state of the art two-dimensional and three-dimensional simulation techniques for such ion beam extraction and transport systems. Furthermore, the main contributions to the ion beam emittance are discussed: (1) The induced beam rotation due to the strong axial magnetic field, (2) the concentration of high charge state ions at the source center axis, and (3) the ion beam temperature. A novel large-gap analyzing magnet design is described which allows efficient correction of higher-order aberrations for high-intensity heavy ion beams. Such a magnet limits emittance blow up, and is necessary if the analyzed beam has to be further transported or accelerated, e.g., in a radio frequency quadrupole. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new 14 GHz ECR ion source for the ATLAS facility is under construction. The new source is an evolution of the 14 GHz AECR Lawrence Berkeley source. The new source will feature an all-aluminum hexapole main chamber and enhanced peak radial and solenoid magnetic fields compared to the existing AECR. Most of the other design features of the existing source are maintained in this design. The new source will be mounted on a new 300 kV high-voltage platform in order to match the velocity requirements of the existing PII injector linac. Achieving the very precise goal of a few electrical microamps of 238U+33 from this source will allow the ATLAS facility to provide Coulomb-barrier energies of uranium without the use of an additional stripper foil and will significantly enhance the capabilities of ATLAS for the heaviest of beams. The project status and more details of the source system design are discussed. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The LBNL third generation electron cyclotron resonance (ECR) ion source has progressed from a concept to the fabrication of a full scale prototype superconducting magnet structure. This new ECR ion source will combine the recent ECR ion source techniques that significantly enhance the production of high charge state ions. The design includes a plasma chamber made from aluminum to provide additional cold electrons, three separate microwave feeds to allow multiple-frequency plasma heating (at 10, 14, and 18 GHz or at 6, 10, and 14 GHz) and very high magnetic mirror fields. The design calls for mirror fields of 4 T at injection and 3 T at extraction and for a radial field strength at the wall of 2.4 T. The prototype superconducting magnet structure which consists of three solenoid coils and six race track coils with iron poles forming the sextupole has been tested in a vertical Dewar. After training, the sextupole magnet reached 105% of its design current with the solenoids off. With the solenoids operating at approximately 70% of their full design field, the sextupole coils operated at 95% of the design value which corresponds to a sextupole field strength at the plasma wall of more than 2.1 T. © 1998 American Institute of Physics.
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  • 7
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Production of high charge state ions with the Advanced Electron Cyclotron Resonance ion source (AECR) at Lawrence Berkeley National Laboratory (LBNL) has been significantly improved by application of various new techniques. Heating the plasma simultaneously with microwaves of two frequencies (10 and 14 GHz) has increased the production of very high charge state heavy ions. The two-frequency technique provides extra electron cyclotron resonance heating zone as compared to the single-frequency heating and improves the heating of the plasma electrons. Aluminum oxide on the plasma chamber surface improves the production of cold electrons at the chamber surfaces and increases the performance of the AECR. Fully stripped argon ions, ≥5 enA, were produced and directly identified by the source charge state analyzing system. High charge state ion beams of bismuth and uranium, such as 209Bi51+ and 238U53+, were produced by the source and accelerated by the 88-in. cyclotron to energies above 6 MeV/nucleon for the first time. © 1996 American Institute of Physics.
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 4218-4221 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The performance of the Lawrence Berkeley Laboratory (LBL) advanced electron cyclotron resonance ion source, which is a single stage source designed to operate at 14 GHz alone (single-frequency heating), is enhanced by heating the plasma simultaneously with microwaves of 10 and 14 GHz (two-frequency heating). Production of high charge state ions was increased a factor of 2–5 or higher for the very heavy ions such as bismuth and uranium, as compared to single- frequency heating. Plasma stability was improved and the ion charge state distribution shifted to higher charge state. With two-frequency heating, the source can produce more than 1×109 pps of fully stripped argon. High charge state ion beams of bismuth and uranium produced by the source were injected into the 88-Inch Cyclotron at LBL. After acceleration to energies greater than 6 MeV/nucleon, the extracted beam intensities were 1×106 pps or higher for Bi50+,51+ and 238U52+,53+. © 1995 American Institute of Physics.
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 62 (1991), S. 775-778 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An electron gun for the advanced electron cyclotron resonance (AECR) source has been developed to increase the production of high charge state ions. The AECR source, which operates at 14 GHz, is being developed for the 88-in. cyclotron at Lawrence Berkeley Laboratory. The electron gun injects 10 to 150 eV electrons into the plasma chamber of the AECR. With the electron gun the AECR has produced at 10 kV extraction voltage 131 e μA of O7+, 13 e μA of O8+, 17 e μA of Ar14+, 2.2 e μA of Kr25+, 1 e μA of Xe31+, and 0.2 e μA of Bi38+. The AECR was also tested as a single stage source with a coating of SiO2 on the plasma chamber walls. This significantly improved its performance compared to no coating, but direct injection of electrons with the electron gun produced the best results.
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