VENUS is a third generation electron cyclotron resonance (ECR) ion source, which incorporates a high field superconducting NbTi magnet structure, a 28 GHz gryotron microwave source and a state of the art closed cycle cryosystem. During the decade from initial concept to regular operation, it has demonstrated both the feasibility and the performance levels of this new generation of ECR ion sources and required innovation on magnet construction, plasma chamber design, and beam transport. In this paper, the development, performance, and major innovations are described as well as a look to the potential to construct a fourth generation ECR ion source.

VENUS (Versatile ECR ion source for NUclear Science) is a next generation superconducting ECR ion source, designed to produce high current, high charge state ions for the 88-Inch Cyclotron at the Lawrence Berkeley National Laboratory. VENUS also serves as the prototype ion source for the RIA (rare isotope accelerator) front end. The goal of the VENUS ECR ion source project as the RIA R&D injector is the production of 200eμA of U30+, a high current medium charge state beam. On the other hand, as an injector ion source for the 88-Inch Cyclotron the design objective is the production of 5eμA of U48+, a low current, very high charge state beam. To achieve those ambitious goals, the VENUS ECR ion source has been designed for optimum operation at 28GHz. The nominal design fields of the axial magnets are 4T at injection and 3T at extraction; the nominal radial design field strength at the plasma chamber wall is 2T, making VENUS currently the world’s most powerful ECR plasma confinement structure. Recently, the six year project has made significant progress. In June 2002, the first plasma was ignited at 18GHz. During 2003, the VENUS ECR ion source was commissioned at 18GHz, while preparations for 28GHz operation were being conducted. In May 2004 28GHz microwave power has been coupled into the VENUS ECR ion source for the first time. Preliminary performance-tests with oxygen, xenon and bismuth at 18GHz and 28GHz have shown promising results. Intensities close to or exceeding the RIA requirements have been produced for those few test beams. The paper will briefly describe the design of the VENUS source and its beam analyzing system. Results at 18GHz and 28GHz including first emittance measurements will be described.

VENUS (Versatile ECR ion source for NUclear Science) is a next generation superconducting ECR ion source, designed to produce high current, high charge state ions for the 88-Inch Cyclotron at the Lawrence Berkeley National Laboratory. VENUS also serves as the prototype ion source for the RIA (Rare Isotope Accelerator) front end. The magnetic confinement configuration consists of three superconducting axial coils and six superconducting radial coils in a sextupole configuration. The nominal design fields of the axial magnets are 4T at injection and 3T at extraction; the nominal radial design field strength at the plasma chamber wall is 2T, making VENUS the world most powerful ECR plasma confinement structure. From the beginning, VENUS has been designed for optimum operation at 28 GHz with high power (10 kW).In 2003 the VENUS ECR ion source was commissioned at 18 GHz, while preparations for 28 GHz operation were being conducted. During this commissioning phase with 18 GHz, tests with various gases and metals have been performed with up to 2000 W RF power. At the initial commissioning tests at 18 GHz, 1100 e mu A of O6+, 160 e mu A of Xe20+, 160 e mu A of Bi25+ and 100 e mu A of Bi30+ and 11 e mu A of Bi41+ were produced.In May 2004 the 28 GHz microwave power has been coupled into the VENUS ECR ion source. At initial operation more than 320 e mu A of Xe20+ (twice the amount extracted at 18 GHz), 240 e mu A of Bi24+ and Bi25+, and 245 e mu A of Bi29+ were extracted. The paper briefly describes the design of the VENUS source, the 28 GHz microwave system and its beam analyzing system. First results at 28 GHz including emittance measurements are presented.

The Rare Isotope Accelerator (RIA) Linac driver requires a great variety of high charge state ion beams with up to a magnitude higher intensity than currently achievable for the heaviest masses. The goal of the RIA injector R&D program for VENUS is the reliable production of intense medium charge state ion beams, e.g. 8 puA (particle µA) of U 29+ . Therefore, the superconducting ECR ion source VENUS has been designed from the beginning for optimum operation at 28 GHz at high power (10 kW). In addition, a high intensity Low Energy Beam Transport, LEBT, that was developed to analyze and transport these multiply-charged, space charge dominated beams. During the last year VENUS was commissioned at 18 GHz and preparations for 28 GHz operation continued. Tests with various gases and recently metals have been performed with up to 2000 W of 18 GHz RF power. Promising performance has been measured in those preliminary beam tests. For example, 180 pµA of O 6+ , 15 pµA of Ar 12+ , 7.5 puA of Xe 20+ and 4puA of Bi 24+ were produced in the early commissioning phase, ranking VENUS among the currently highest performance 18 GHz ECR ion sources. In FY04 a 10 kW 28 gyrotron system will be added, which will enable VENUS to reach full performance. The emittance of the beams produced at 18 GHz was measured with a two axis emittance scanner developed with earlier RIA R&D funds.

During the last year, the VENUS ECR ion source was commissioned at 18 GHz and preparations for 28 GHz operation, which is set to begin early in 2004, are now underway. The goal of the VENUS ECR ion source project as the RIA R&D injector is the production of 240emA of U30+, a high current medium charge state beam. On the other hand, as an injector ion source for the 88-Inch Cyclotron the design objective is the production of 5emA of U48+, a low current, very high charge state beam. During the commissioning phase with 18 GHz, tests with various gases and recently metals have been performed with up to 2000 W RF power and the performance is very promising. For example, 1100 e mu A of O6+,180 e mu A of Ar12+, 150 emA of Xe20+ and 100 emA of Bi24+ were produced in the early commissioning phase, ranking VENUS among the currently highest performance 18 GHz ECR ion sources. The emittance of the beams produced at 18 GHz was measured with a two axis emittance scanner. In FY04 a 10 kW, 28 GHz gyrotron system will be added, which will enable VENUS to reach full performance. The performancemore » of the VENUS ion source, low energy beam transport (LEBT) and its closed loop cryogenic system are described in the paper. Recently, a new high temperature axial oven has been installed in the source and the first results on metal beams such as bismuth are given. The design of the 28 GHz, 10 kW gyrotron system is also be described. During the last year, the VENUS ECR ion source was commissioned at 18 GHz and preparations for 28 GHz operation, which is set to begin early in 2004, are now underway. The goal of the VENUS ECR+, a high current medium charge state beam. On the other hand, as an injector ion source for the 88-Inch Cyclotron the design objective is the production of 5 emA of U48+, a low current, very high charge state beam. During the commissioning phase with 18 GHz, tests with various gases and recently metals have been performed with up to 2000 W RF power and the performance is very promising. For example, 1100 e mu A of O6+, 180 e muA of Ar12+, 150 emA of Xe20+ and 100 emA of Bi24+ were produced in the early commissioning phase, ranking VENUS among the currently highest performance 18 GHz ECR ion sources. The emittance of the beams produced at 18 GHz was measured with a two axis emittance scanner. In FY04 a 10kW, 28 GHz gyrotron system will be added, which will enable VENUS to reach full performance. The performance of the VENUS ion source, low energy beam transport (LEBT) and its closed loop cryogenic system are described in the paper. Recently, a new high temperature axial oven has been installed in the source and the first results on metal beams such as bismuth are given. The design of the 28 GHz, 10 kW gyrotron system is also be described.« less

During the last year, the VENUS electron cyclotron resonance (ECR) ion source was commissioned at 18 GHz and preparations for 28 GHz operation, which is set to begin early in 2004, are now underway. The goal of the VENUS ECR ion source project as the RIA research and development injector is the production of 240 eμA of U30+, a high current medium charge state beam. On the other hand, as an injector ion source for the 88-Inch Cyclotron the design objective is the production of 5 eμA of U48+, a low current, very high charge state beam. During the commissioning phase with 18 GHz, tests with various gases and recently metals have been performed with up to 2000 W rf power and the performance is very promising. For example, 1100 eμA of O6+, 180 eμA of Ar12+, 150 eμA of Xe20+, and 100 eμA of Bi24+ were produced in the early commissioning phase, ranking VENUS among the currently highest performance 18 GHz ECR ion sources. The emittance of the beams produced at 18 GHz was measured with a two axis emittance scanner. In FY04 a 10 kW, 28 GHz gyrotron system will be added, which will enable VENUS to reach full performance. The performance of the VENUS ion source, low energy beam transport and its closed loop cryogenic system are described in the article. Recently, a high temperature axial oven has been installed in the source and the first results on metal beams such as bismuth are given. The design of the 28 GHz, 10 kW gyrotron system will also be described.

The magnet system of the VENUS ECR Ion Source at LBNL has two 1.5-watt cryocoolers suspended in the cryostat vacuum. Helium vapor from the liquid reservoir is admitted to a finned condenser bolted to the cryocooler 2nd stage and returns as liquid via gravity. Small-diameter flexible tubes allow the cryocoolers to be located remotely from the reservoir. With 3.1 watts load, the helium reservoir is maintained at 4.35 K, 0.05K above the cryocooler temperature. Design, analysis, and performance are presented.

VENUS (Versatile ECR ion source for NUclear Science) is a next generation superconducting ECR ion source, designed to produce high current, high charge state ions for the 88-Inch Cyclotron at the Lawrence Berkeley National Laboratory. VENUS also serves as the prototype ion source for the RIA (Rare Isotope Accelerator) front end. The magnetic confinement configuration consists of three superconducting axial coils and six superconducting radial coils in a sextupole configuration. The nominal design fields of the axial magnets are 4T at injection and 3T at extraction; the nominal radial design field strength at the plasma chamber wall is 2T, making VENUS the world most powerful ECR plasma confinement structure. The magnetic field strength has been designed for optimum operation at 28 GHz. The four-year VENUS project has recently achieved two major milestones: The first plasma was ignited in June, the first mass-analyzed high charge state ion beam was extracted in September of 2002. The paper describes the ongoing commissioning. Initial results including first emittance measurements are presented.

The construction of VENUS, a next generation superconducting Electron Cyclotron Resonance ion source designed to operate at 28 GHz, is complete. The cryostat including the superconducting magnet assembly was delivered in September 2001. During acceptance tests, the superconducting magnets produced an axial magnetic field strength of 4T at injection, 3T at extraction, and a radial field strength of 2T at the plasma chamber wall without any quenches. These fields are sufficient for optimum operation at 28 GHz. The cryogenic system for VENUS has been designed to operate at 4.2 K with two cryocoolers each providing up to 45 W of cooling at 50 K and 1.5 W at 4 K in a closed loop mode without further helium transfers. However, during the acceptance tests an excessive heat leak of about 3W was measured. In addition, the liquid helium heat exchanger did not work properly and had to be redesigned. The cryogenic system modifications will be described. In addition, an update on the installation of the ion source and its beam line components will be given.

The low energy beam transport (LEBT) for VENUS will provide for extraction, mass analysis and transport to the axial injection line for the 88-Inch Cyclotron. The new LEBT was designed from the beginning to handle high intensity beams where space charge forces strongly affect the transmission. The magnet has a unique design with specially shaped poles to apply sextupole correction in both the horizontal and vertical plane.

The construction of VENUS, an Electron Cyclotron Resonance ion source designed to operate at 28 GHz, is nearing completion. Tests with the superconducting magnet assembly produced axial magnetic field strengths of 4 T at injection and 3 T at extraction and a sextupole field of 2 T at the plasma wall. These fields are sufficient for optimum operation at 28 GHz. We expect a shift to higher charge states and an increase in the beam intensities (about 4 times) compared to those obtained with the AECR-U, which operates at 14 GHz. Initial operation will be at 18 GHz, but best performance is expected when operation with a 10 kW, 28 GHz gyrotron becomes possible. The high beam intensities and the large axial magnetic field at extraction make it challenging to extract, analyze and transport the beam into the 88-Inch Cyclotron. The analyzing system which consists of a solenoid lens and a large gap 18 cm spectrometer-magnet with higher order field corrections has been optimized utilizing 3D magnet and ray-tracing codes including space charge effects, The status of the construction and design aspects of the source and beam transport system are described below.

A new, very high magnetic field superconducting ECR ion source, VENUS, is under development at the LBNL 88-Inch Cyclotron. It will boost the maximum energies and intensities for heavy ions from the cyclotron particularly for ions with mass greater than 60. It will also serve as R&D ion source for the proposed Rare Isotope Accelerator (RIA) project in the US, which requires up to 10 p muA of U30+. The superconducting magnet structure consists of three solenoids and six racetrack coils with iron poles forming the sextupole. The coils are designed to generate a 4 Taxial mirror field at injection and 3 Tat extraction and a radial sextupole field of 2.4 Tat the plasma chamber wall. Test results of the magnet coils, which exceeded design requirements with minimum training, are presented. The magnet assembly with its cryostat will be enclosed by an iron shield and therefore must be designed to withstand any possible forces between coils and iron, which can be as high as 3.4.10(5) N (35,000 kgf). The low energy beam transport line (LEBT) and mass analyzing system of the ion source is designed to transport a proton-equivalent current of 25 mA at 20 kV extraction voltage. The design of the ion source and LEBT will be discussed.

A new, very high magnetic field superconducting ECR ion source, VENUS, is under development at the LBNL 88-Inch Cyclotron. It will boost the maximum energies and intensities for heavy ions from the cyclotron particularly for ions with mass greater than 60. It will also serve as R&D ion source for the proposed Rare Isotope Accelerator (RIA) project in the US, which requires up to 10 pµA of U 30+ . The superconducting magnet structure consists of three solenoids and six racetrack coils with iron poles forming the sextupole. The coils are designed to generate a 4T axial mirror field at injection and 3T at extraction and a radial sextupole field of 2.4 T at the plasma chamber wall. Test results of the magnet coils, which exceeded design requirements with minimum training, are presented. The magnet assembly with its cryostat will be enclosed by an iron shield and therefore must be designed to withstand any possible forces between coils and iron, which can be as high as 35,000 kg-force. The low energy beam transport line (LEBT) and mass analyzing system of the ion source is designed to transport a proton-equivalent current of 25mA at 20kV extraction voltage. The design of the ion source and LEBT will be discussed.

Using improved selection techniques, we isolated four monoclonal antibodies with high affinity for human thyrotropin (Ka = 1.6 X 10(8) to 2.6 X 10(10) L/mol). We used two of these in an immunoradiometric assay (IRMA) that also incorporates a novel phase-separation technology (Sucrosep TSH IRMA, Boots-Celltech). This assay's very low detection limit for TSH (0.03-0.08 milli-int. unit/L) and wide working range (0-250 milli-int. unit/L) allow the differential diagnosis of hypothyroid, euthyroid, and hyperthyroid patients. We compare the utility of this IRMA with that of a RIA for patients with various thyroid disorders. As determined by IRMA, a normal concentration of TSH in serum excludes hyperthyroidism or hypothyroidism, whereas an undetectable serum TSH concentration (less than 0.08 milli-int. unit/L) accurately predicts an abnormality in thyroid gland function.

Peripheral blood mononuclear cells (PBMC) derived from healthy individuals were stimulated with u.v.-inactivated Newcastle disease virus and the cell supernatants were assayed for both antiviral activity and alpha interferon (IFN-alpha) immunoreactivity. IFN-alpha concentrations determined by two immunoradiometric assays (IRMAs) based on monoclonal antibodies that recognize different IFN-alpha subtypes correlated well together (r = 0.96) and with interferon concentrations determined by the two bioassays (r = 0.82 to 0.89), but the agreement between the results of the two bioassays was not as close (r = 0.79). As judged by the agreement between determinations on duplicate inductions of the same PBMC, the IRMAs were considerably more precise than the bioassays. Despite the use of a common IFN standard there were marked differences in the absolute titres of IFN determined by the IRMAs and bioassays, highlighting the difficulties in standardizing assays for IFN-alpha. The IRMA results suggest that there are no major differences in the spectrum of IFN-alpha subtypes produced by healthy individuals under conditions of viral stimulation.