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ABSTRACT: The emittances of hydrogen and deuterium negative ion beams produced by volume ion sources have been measured in a transverse plane normal to the beam trajectory. The extraction voltage was varied from 10 to 40 kV, and the transverse magnetic field in the Penning discharges was varied from 0.1 to 0.2 T. Measurements were made on beams with current densities up to 60 mA/cm<sup>2</sup> at Oak Ridge National Laboratory with an emittance scanner originally developed at Los Alamos National Laboratory. The beam profile at the scanner can be used to improve the accuracy of the emittance measurements. Other factors affecting emittance measurements are discussed. This analysis may be applicable to other ion sources.
Review of Scientific Instruments 03/1990; · 1.37 Impact Factor
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ABSTRACT: The next-generation fusion devices based on the tokamak confinement concept are expected to emphasize steady-state operation. Such future reactors may include designs like the International Thermonuclear Experimental Reactor (ITER) and that of the recent International Tokamak Reactor (INTOR) program. Effective means of non-inductive plasma current drive would therefore be necessary. This paper describes a neutral beam concept for a current drive system (which will heat the plasma as well) that is based on negative ions and has a beam energy > 1 MeV. Such systems, at much lower power levels, are also being considered for alpha diagnostics. Preliminary physics calculations show that the plasma core current necessary for stability enhancement can best be achieved in these future reactor-like machines with tangentially injected beams having energies ranging from 1 to 4 MeV. Further study and experiments will better define the optimum energy. Studies of how to accomplish beams of this energy led to the system described in this paper.
02/1989
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ABSTRACT: An electrostatic emittance scanner has been used to measure the emittance of intense H/sup -/ and D/sup -/ beams formed by ion sources developed at the Oak Ridge National Laboratory (ORNL). The ion sources have been operated reliably in both the Surface Ionization with Transverse Extraction (SITEX) and Volume Ionization with Transverse Extraction (VITEX) modes. The emittance measurements were made in a magnetic field of about 1 kg. The effective dimensions of the beamlet sample at the accelerator exit in the SITEX mode were 0.21 cm by 0.16 cm. (Here 0.16 cm is the central part of a 12.7-cm beam ribbon that is parallel to the applied source magnetic field.) The normalized rms emittances for such SITEX beamlets (approx.1.14 mA) were 0.01 ..pi.. . cm. mrad measured transverse to the field and 0.003 ..pi.. . cm . mrad measured parallel to the field for 10-keV D/sup -/ beams (36 mA/cm/sup 2/). The dimensions of H/sup -/ beams at the accelerator exit in the VITEX mode were 0.1 cm by 2.0 cm. The normalized rms emittances were about 0.013 ..pi.. . cm . mrad measured transverse to the field and 0.017 ..pi.. . cm . mrad measured parallel to the field for 15-keV, 12-mA (or 60-mA/cm/sup 2/) beams. The highest current density achieved is above 150 mA/cm/sup 2/. Ion temperatures obtained from the parallel emittance measurements were 9.4 eV for SITEX beams and 0.6 eV for VITEX beams. In this report, the method used to analyze the measured emittance data is described, and the potential errors in measurement are discussed. 9 refs., 16 figs., 1 tab.
10/1987;
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ABSTRACT: Surface ionization with Transverse Extraction (SITEX) and Volume Ionization with Transverse Extraction (VITEX) ion sources are being developed to produce intense beams of light negative ions for neutral particle beam applications. The salient feature of these ion sources is their ability to form intense negative‐ion beams. With the objective of improving the performance of these sources, an experimental study of their plasma properties has been conducted. The effects of various electrodes in the plasma generator were investigated. Low electron and ion temperatures (below 1 eV) and positive plasma potential up to +6V have been measured. The measured distributions of plasma density and potential reveal the existence of multichamber characteristics in the source plasma. The significant discharge characteristics and the plasma properties associated with the performance of SITEX and VITEX ion sources are discussed.
AIP Conference Proceedings. 07/1987; 158(1):194-205.
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ABSTRACT: Beam parameters have been measured for both the Surface Ionization with Transverse Extraction (SITEX) and Volume Ionization with Transverse Extraction (VITEX) H−/D− ion sources. Both sources use a reflex discharge to generate the main plasma. Beam energies up to 18 keV were used for pulse lengths up to several seconds. For SITEX, Faraday cup magnetically analyzed D− beam currents of 110 mA at extraction densities of 48 mA/cm2 and at a source ion temperature of 4 eV have been measured. For the VITEX results, Faraday cup magnetically analyzed beam currents of up to 80 mA at extraction densities of 27 mA/cm2 and at a source ion temperature of 0.5 eV have been measured. Virtually all extracted electrons were recovered at an energy of 10–30% of the accel beam energy, and there were none in the analyzed beam.
AIP Conference Proceedings. 07/1987; 158(1):366-377.
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ABSTRACT: Beam parameters have been measured for both the Surface Ionization with Transverse Extraction (SITEX) and Volume Ionization with Transverse Extraction (VITEX) H/sup -//D/sup -/ ion sources. Both sources use a reflex discharge to generate the main plasma. Beam energies up to 18 keV were used for pulse lengths up to several seconds. For SITEX, Faraday cup magnetically analyzed D/sup -/ beam currents of 110 mA at extraction densities of 48 mA/cm/sup 2/ and at a source ion temperature of 4 eV have been measured. For the VITEX results, Faraday cup magnetically analyzed beam currents of up to 80 mA at extraction densities of 27 mA/cm/sup 2/ and at a source ion temperature of 0.5 eV have been measured. Virtually all extracted electrons were recovered at an energy of 10 to 30% of the accel beam energy, and there were none in the analyzed beam.
12/1985
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M. M. Menon,
C. C. Tsai,
J. H. Whealton,
D. E. Schechter,
G. C. Barber,
S. K. Combs, W. K. Dagenhart,
W. L. Gardner,
H. H. Haselton,
N. S. Ponte,
P. M. Ryan,
W. L. Stirling,
R. E. Wright
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ABSTRACT: A quasi‐steady‐state (pulse duration of 30 s) ion source of the duoPIGatron type has been developed for fusion applications. It was designed to deliver an 80‐keV hydrogen ion beam of low beamlet divergence (Θ rms = 0.26°) at a current density of 0.19 A cm<sup>-</sup><sup>2</sup>. Hydrogen ion beams of 40 to 48 A were extracted at beam energies of 77 to 80 keV for 30‐s‐long pulses. The reliability and stability of the ion source operation were demonstrated by extracting about 600 beam pulses at full power and full pulse length. The ion source was also operated with deuterium as the working gas, and the optimum current at 80 keV was found to be about 33 A, in agreement with the expected inverse square‐root scaling of current density with atomic mass.
Review of Scientific Instruments 03/1985; · 1.37 Impact Factor
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ABSTRACT: An emittance measurement employing two techniques are being made on SITEX. To this end, a 2‐D calculation was performed to design the accelerator in order to reduce electric field aberrations. The calculated normalized emittance is 6×10−4 πcm mrad for an angular divergence θRMS≊0.280. Status of the experimental findings are presented and a comparison made to the calculated value which will yield the ion sputter energy.
AIP Conference Proceedings. 02/1984; 111(1):450-457.
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ABSTRACT: Conceptual and preliminary engineering design for the National RF Test Facility at Oak Ridge National Laboratory (ORNL) has been completed. The facility will comprise a single mirror configuration embodying two superconducting development coils from the ELMO Bumpy Torus Proof-of-Principle (EBT-P) program on either side of a cavity designed for full-scale antenna testing. The coils are capable of generating a 1.2-T field at the axial midpoint between the coils separated by 1.0 m. The vacuum vessel will be a stainless steel, water-cooled structure having an 85-cm-radius central cavity. The facility will have the use of a number of continuous wave (cw), radio-frequency (rf) sources at levels including 600 kW at 80 MHz and 100 kW at 28 GHz. Several plasma sources will provide a wide range of plasma environments, including densities as high as approx. 5 x 10/sup 13/ cm/sup -3/ and temperatures on the order of approx. 10 eV. Furthermore, a wide range of diagnostics will be available to the experimenter for accurate appraisal of rf testing.
12/1982
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ABSTRACT: A quasi-steady-state ion source has been developed for neutral beam injection applications. It is of the duoPIGatron type designed for delivering 50 A of hydrogen ions at 80 keV for 30-s-long pulses. Ion beams of 40 A at 75 keV were extracted for pulse lengths up to 30 s, maintaining excellent optical quality in the beam for the entire pulse duration. The design features and operational characteristics of the ion source are elaborated.
12/1982
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W. L. Gardner,
G. C. Barber,
C. W. Blue, W. K. Dagenhart,
H. H. Haselton,
J. Kim,
M. M. Menon,
N. S. Ponte,
P. M. Ryan,
D. E. Schechter,
W. L. Stirling,
C. C. Tsai,
J. H. Whealton,
R. E. Wright
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ABSTRACT: The properties of an intense 50‐kV neutral‐beam system are discussed. The salient features of this system are a transmission efficiency of 76% of the extracted ion beam through a 30×34 cm aperture that is 4.5 m from the ion source, a transmitted neutral power of 1.8 MW H<sup>0</sup> (2.0 MW D<sup>0</sup>) at extraction parameters of 50 kV/100 A/0.1 s (53 kV/85 A/0.1 s), a proton fraction of ∼80%, an ion‐source arc efficiency of ∼1.3 A/kW, an ion‐source gas efficiency of ∼35%, and a reliability of ≳90%.
Review of Scientific Instruments 05/1982; · 1.37 Impact Factor
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ABSTRACT: Parametric studies were made on a hot cathode reflex discharge H/sup -/ Surface Ionization source with Transverse Extraction (SITEX) in both the pure hydrogen and the mixed hydrogen-cesium mode. Extraction current density, beam current, gas efficiency, extracted electron-to-H/sup -/ current ratio, heavy negative ion impurities, optics, and long pulse operation were investigated as a function of time, arc voltage, arc current, converter voltage, H/sub 2/ gas flow, cesium feed rate, and plasma generator geometries. Initial results of the research were an extracted H/sup -/ beam current density of 56 mA/cm/sup 2/ at 23 mA for 5 s pulses and, gas efficiency of 3%, theta/sub perpendicular/ (1/e) approx. 2 +- 1/sup 0/, theta/sub parallel/ (1/e) approx. 1 +- 1/sup 0/, at a beam energy of 25 keV. Negative heavy ion beam impurities were reduced to < 1% at low current densities. H/sup -/ ions are produced prinicpally by positive ion surface conversion using elemental cesium fractional monolayer coverage on a molybdenum converter substrate, which is biased negatively with respect to the anode.
04/1982;
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ABSTRACT: This paper describes the development of a long-pulse positive ion source that has been designed to provide high brightness deuterium beams (divergence approx. = 0.25/sup 0/ rms, current density approx. = 0.15 A cm/sup -2/) of 40 to 45 A, at a beam energy of 80 keV, for pulse lengths up to 30 s. The design and construction of the ion source components are described with particular emphasis placed on the long-pulse cathode assembly and ion accelerator.
12/1981
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W. L. Gardner,
J. H. Whealton,
G. C. Barber,
C. W. Blue, W. K. Dagenhart,
H. H. Haselton,
J. Kim,
M. M. Menon,
N. S. Ponte,
P. M. Ryan,
D. E. Schechter,
W. L. Stirling,
C. C. Tsai,
R. E. Wright
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ABSTRACT: Experimental comparison is made of four plasma grids, each with a specific aperture geometry, in an attempt to improve the ion optics of a multiple aperture ion source. It is clearly shown that a simple notch geometry outperforms the other candidates with a high transmission efficiency (∼68%) to a 2° target at high perveance (∼9.6 μperv).
Review of Scientific Instruments 12/1981; · 1.37 Impact Factor
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W. L. Stirling,
G. C. Barber, W. K. Dagenhart,
R. R. Feezell,
W. L. Gardner,
H. H. Haselton,
J. Kim,
M. Menon,
N. S. Ponte,
C. C. Tsai,
J. H. Whealton
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ABSTRACT: The injection of neutral hydrogen or deuterium particles continues to be the most promising means of heating magnetically confined fusion plasmas to ignition temperatures. Neutral beam injection systems that employ positive ion sources presently operate at energies of about 40-50 keV/nucleon at 60 A [Princeton Large Torus (PLT)] or 100 A [Princeton Divertor Experiment (PDX) or the Oak Ridge National Laboratory (ORNL) Impurities Study Experiment (ISX)] with about 60% conversion efficiency. However, the desire for multisecond beams in the 80-keV/nucleon energy range at ~ 10 MW/module has emphasized the need for technological advances in several areas. At such beam energies, as much as 75% of the initial beam energy is retained in the unneutralized ion components. As a result, two questions immediately come to mind: (1) how can one dispose of this energy; or better still, (2) how can one efficiently recover this energy? The conventional way of treating such a problem is to deflect the ions out of the neutral beam and onto water-cooled plates or beam dumps. This method has worked satisfactorily for 40-keV/nucleon beams in excess of 1.5 MW and ~0.5 s. However, the power per unit area to be disposed of in the high power, multisecond beams mentioned above is beyond present-day technology.
IEEE Transactions on Nuclear Science 05/1981; · 1.45 Impact Factor
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ABSTRACT: Two PLT‐injector‐type duoPIGatron sources, modified further by shaping the beam‐forming apertures, have been tested and experimented on a protype beam line similar to the ISX‐B neutral beam injection system. The accelerator column modification has resulted in an increase of the beam power transmission efficiency from that of the straight‐bore aperture by 50%. Maximum neutral beam powers achieved on a 28‐cm‐diam target simulating the ISX‐B plasma, located 4.1 m downstream from the source, are ?910 kW of H<sup>0</sup> at an accelerator power of 42 kV and 61 A and ?1020 kW of D<sup>0</sup> at 43 kV and 55 A. Measurements have been made to investigate the following: the effects on beam optics of aperture shape, aspect ratio, and different ions (H<sup>+</sup> or D<sup>+</sup>); the distribution of beam power deposition along the beam line; ion species compositions; and background pressure behavior due to scrape‐off beam particles. The injectors have been shown to be characterized by an optimum perveance of 6×10<sup>-6</sup> AV<sup>-3/2</sup> for an effective extraction area of 142 cm<sup>2</sup> (1799 apertures), which is approximately invariant over the beam energies tried (viz., 25‐45 keV).
Journal of Applied Physics 05/1980; · 2.17 Impact Factor
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ABSTRACT: Negative ion generation has advanced rapidly by employing the concept of surface ionization. The modified calutron has proven to be a successful tool to explore these concepts and provide solutions to the many problems which must be evaluated. Many features of the SITEX (Surface Ionization with Transverse Extraction) ion source are ideally suited to this exploration. Some of these features are; a ribbon-like plasma, electron control by transverse magnetic fields and the ability to separate the Cs oven parameters from those which control the positive ion generation.
12/1979
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W. L. Stirling,
J. Kim,
H. H. Haselton,
G. C. Barber,
R. C. Davis, W. K. Dagenhart,
W. L. Gardner,
N. S. Ponte,
C. C. Tsai,
J. H. Whealton,
R. E. Wright
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ABSTRACT: A method is described for making positive‐ion‐based neutral‐beam injection viable at energies of ≲100 keV per nucleon by recovering the energy of residual charged particles as electrical energy. The concept of transverse magnetic field blocking of electrons has been shown to be successful, and preliminary experimental results are presented.
Applied Physics Letters 08/1979; · 3.84 Impact Factor
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W L Stirling,
C C Tsai,
H H Haselton,
D E Schechter,
J H Whealton, W K Dagenhart,
R C Davis,
W L Gardner,
J Kim,
M M Menon,
P M Ryan
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ABSTRACT: The properties of an intense neutral beam injector, the modified duoPIGatron ion source, are discussed and compared with other injectors. For this source (a) beam composition for hydrogen is approximately (85+/-5) % monatomic, (b) nucleon gas efficiency is 50%, (c) the electrical efficiency of ion generation is 1.1 A/kW, and (d) up to 52% of the input power is delivered in the ion and neutral beam to a target subtending a half angle of 1.8 degrees x1.4 degrees .
Review of Scientific Instruments 06/1979; 50(5):523. · 1.37 Impact Factor
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W. L. Stirling,
C. C. Tsai,
H. H. Haselton,
D. E. Schechter,
J. H. Whealton, W. K. Dagenhart,
R. C. Davis,
W. L. Gardner,
J. Kim,
M. M. Menon,
P. M. Ryan
[show abstract]
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ABSTRACT: The properties of an intense neutral beam injector, the modified duoPIGatron ion source, are discussed and compared with other injectors. For this source (a) beam composition for hydrogen is ∼ (85±5) % monatomic, (b) nucleon gas efficiency is 50%, (c) the electrical efficiency of ion generation is 1.1 A/kW, and (d) up to 52% of the input power is delivered in the ion and neutral beam to a target subtending a half angle of 1.8°×1.4°.
Review of Scientific Instruments 06/1979; · 1.37 Impact Factor
