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An electron cyclotron resonance (ECR) multicusp plasmatron has been developed by feeding a multicusp bucket arc chamber with a compact ECR plasma source. This novel source produces large (about 25 cm diam), uniform (to within ±10%), dense (>1011 cm−3) plasmas of argon, helium, hydrogen, and oxygen. It has been operated to produce an oxygen plasma for etching 12.7 cm (5 in.) positive photoresist‐coated silicon wafers with uniformity within ±8%. Results and potential applications of this new ECR plasma source for plasma processing of thin films are discussed.An electron cyclotron resonance (ECR) multicusp plasmatron has been developed by feeding a multicusp bucket arc chamber with a compact ECR plasma source. This novel source produces large (about 25 cm diam), uniform (to within ±10%), dense (>1011 cm−3) plasmas of argon, helium, hydrogen, and oxygen. It has been operated to produce an oxygen plasma for etching 12.7 cm (5 in.) positive photoresist‐coated silicon wafers with uniformity within ±8%. Results and potential applications of this new ECR plasma source for plasma processing of thin films are discussed.

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/cm2 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.

A concept for a current drive system that is based on negative ions with beam energies >1 MeV is presented. Preliminary physics calculations, which are discussed, show that the core current necessary for stability enhancement can be achieved by beams with energy ranging from 1 to 3 MeV. Further study and experiments will better define the optimum energy. Work under way at Oak Ridge National Laboratory, at AccSys Technology Inc., and at collaborating institutes in the United States, Canada, and the Federal Republic of Germany is continuing to define systems, their elements, configurations, and operational scenarios deemed appropriate for such devices as ITER (International Thermonuclear Experimental Reactor) ARIES (Advanced Reactor Innovation and Evaluation Study), and other future steady-state tokamaks. The cost of the RF-accelerated beam should be quite competitive with DC beam concepts being considered for current drive. Not only would the cost per unit power for the RF concept be attractive but the development costs and time also should be quite reasonable. >

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/cm2 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.

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).

A rectangular ion source is being developed for producing 120‐keV/25‐A hydrogen ion beams for pulse durations up to 10 s. It consists of a plasma generator with a rectangular arc chamber (25×35 cm cross section) and an ion accelerator with rectangular grids (10×25 cm hole pattern). The plasma generator is a modified duoPIGatron type. It has been operated at 120 V, 1100 A, and 10 s arc durations to produce a dense and uniform plasma sufficient for supplying a 25‐A ion beam current. The electron emitter used is either a LaB6 hollow cathode or a LM (molybdenum doped with La2O3) indirectly heated cathode. The ion accelerator having four (or three) rectangular grids with multiple circular apertures has been utilized to form high‐energy ion beams above (or below) 80 keV. With substantial improvements in water cooling and mechanical stability, this ion accelerator has been operated reliably to deliver long‐pulse ion beams with energies in excess of 100 keV and pulse lengths of many seconds. The results of measur...

The results of a systematic investigation of the power flow along the Oak Ridge National Laboratory/Princeton Large Torus (ORNL/PLT) neutral beam line, using an intense modified duoPIGatron source with a 22‐cm active grid diameter and 1799 circular apertures that provide 53% transparency, are reported. The variation of power deposited on the different components of the beam line is measured over a wide range of perveance values. The maximum efficiency for beam power transmitted through a 20×25‐cm aperture located 4.1 m downstream was found to be 41%. This efficiency was raised to 53% when a voltage of about 175 V was applied to preaccelerate the ions entering the extraction apertures. Transmission efficiencies approaching 60% were obtained using shaped apertures on the plasma grid. Higher efficiencies should be attainable when used for PLT injection since the acceptance angle for the Princeton tokamak is 11% higher than that of the test facility. Detailed analysis of the results using straight circular ap...

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.

Beam power transmission and grid loading characteristics of a two‐stage neutral beam source are presented. The dependence of power deposition on the target, the grids, and the gas cell was studied over a wide range of extraction perveance values with the accel‐to‐extraction gap field ratio as the other parameter. The results show that the power transmission improves remarkably with increasing field ratio. For sufficiently large field ratios (≈2.5), more than 80% of the input IV power was collected on a target located 4 m downstream and subtending 2 ° half angle to the source. The sum of the grid loading is approximately double that of single‐stage accelerators; the plasma grid loading is the highest, followed by ground grid, accel grid, and extraction grid in that order.

Analytic solutions to the rate equations describing the species evolution of a multispecies positive ion beam of hydrogen due to charge exchange and molecular dissociation are derived as a function of the background gas (H2) line density in the neutralizing gas cell and in the drift tube. Using the solutions, calculations are presented for the relative abundance of each species as a function of the gas‐cell thickness, the reionization loss in the drift tube, and the neutral‐beam power as a function of the beam energy and the species composition of the original ion beam.

An extension of projectile-electron spectroscopy to keV-energy alkali- metal beams has permitted the first observations of the energies of a number of optically forbidden core-excited autoionizing states of the alkali metals. For example, the (1s2s$sup 2$)$sup 2$S and the (1s2p$sup 2$)$sup 2$D states of Li which lie at 56.31 +- 0.03 eV and 61.04 +- 0.03 eV, respectively, above the ground state have been located. Energies for theoretically less-well-established doublet and quartet states in Na, Mg$sup +$, and K are also presented. 10 figures, 3 tables, 20 references. (auth)

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 H0 (2.0 MW D0) 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%.

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.

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 (Θrms= 0.26°) at a current density of 0.19 A cm−2. 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.

Ion beam technology has advanced immensely during the past 15 years in connection with the application of neutral beam injection heating for fusion research. Ion sources have been scaled up along with necessary modifications, yielding currently a few megawatts of extraction power (e. g., 40 keV-60 A, 0.3-sec pulse). The entire neutral beam injection system has become a multidisciplinary technology including plasma physics, accelerator and beam physics, pumping technology, heat transfer, electrical engineering, and so on. Since the neutral beam injection heating of fusion plasmas has been proved the most viable means of increasing the plasma temperature to ignition, the future demand and requirements are rising with the size of fusion plasma devices. A brief review of the state of the art of neutral beam technology is presented and the direction of the future neutral beam field is discussed.

The foil-excitation method has been used to study the extreme ultraviolet spectra of highly ionized oxygen and fluorine. Several previously unreported lines in heliumlike fluorine are reported and other newly reported lines in heliumlike oxygen have been measured to higher accuracy. Included in the measurements are certain heliumlike oxygen transitions of significance in interpretation of solar-flare spectral observations. The wavelength determinations are usually in good agreement with calculated results which includes relativistic corrections, but discrepancies arise when nonrelativistic calculations are used. A comparison of the present results and those recently obtained by theta-pinch and laser-induced plasma sources is made for both heliumlike and lithiumlike ions; a few discrepancies occur, with results in most cases in better agreement with relativistically corrected calculations. Certain unidentified lines in the spectra may be attributable to radiative transitions between quartet states of lithiumlike ions.

A high‐heat‐flux target has been developed for intercepting multimegawatt, multisecond neutral beams at Oak Ridge National Laboratory (ORNL). Water‐cooled copper swirl tubes are used for the heat transfer medium; these tubes exhibit an enhancement in burnout heat flux over conventional axial flow tubes. The target consists of 126 swirl tubes [each 0.95 cm in outside diameter (o.d.) with 0.16‐cm‐thick walls and ≊1 m long] arranged in a V shape and inclined with respect to the beam axis. In tests with the ORNL long‐pulse ion source (13×43‐cm grid), the target has handled up to 3‐MW, 30‐s beam pulses with no deleterious effects. The peak power density was estimated at ≊15 kW/cm2 normal to the beam axis (>5 kW/cm2 maximum on tube surfaces). The water flow rate through the tubes was 0.33 l/s (5.2 gal/min) per tube (axial flow velocity=11.6 m/s) with a corresponding pressure drop of 1.14 MPa (165 psi). To date, the target has absorbed an estimated 25 000 full‐power (≊3 MW) pulses for a cumulative time of ≊100 0...

Radiofrequency quadrupole accelerator designs were investigated as to their suitability for tokamak current drive applications. Designs are presented for both proton and deuteron machines. The effect of ion source voltage is also discussed. These studies show that one can obtain acceptable beam transmission for a large range of input emittance values. The overall results with respect to beam dynamics are encouraging; the design studies indicate that a 1–2 A beam at 2 MeV is feasible.

The lifetime and binding energy of the lowest-lying metastable quartet state, $(1s2s2p)^{4}p\ifmmode^\circ\else\textdegree\fi{}_{\frac{5}{2}}$ in ${\mathrm{S}}^{13+}$ have been measured by studying the forbidden (spin-spin-induced) autoionizing decay in flight of the state after foil excitation. The state is found to be bound by -4988 \ifmmode\pm\else\textpm\fi{} 26 eV and has a lifetime of 1.1 \ifmmode\pm\else\textpm\fi{} 0.1 nsec. A summary of our previous measurements of these same quantities for other members of the lithiumlike sequence is also given, along with an estimate of the branching ratio for the autoionization process.

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.

Excitation processes in atoms or ions usually involve the promotion of one of the least tightly bound outer shell electrons to a higher orbital leading to a state lying below the ionization threshold. It is possible however to form highly excited discrete states that are embedded in the continuum if one or more inner core electrons are raised to outer shells. In the present paper we report on such states in high Z 3-electron ions associated with core excited configurations of the type 1s2snl and 1s2pnl. Such states may autoionize rapidly via the Coulomb interaction unless forbidden to do so by selection rules on this process. These metastable autoionizing states either decay by radiation or autoionize at a slower rate via the weaker magnetic interactions. The lowest lying quartet state in 3-electron ions (1s2s2p)4P 5/2 o is metastable against both autoionization and radiation. Our previously measured lifetimes [1] for this state (in nanoseconds) are: S (1.1), Si (2.1), Ar (0.66), Cl (0.91), F (15), and 0 (25). Radiative decay processes involving core-excited states have also been previously observed. For example, one type of decay is an El transition between two metastable quartet states and another is a similar transition from a core excited state to a singly excited state.

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.

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 .

Thin, pure, hard carbon films about 1 pm thick have been deposited on a water-cooled copper plate installed in a continuous-wave (cw) plasma source with graphite walls. The transparent, glassy films were observed after several thousand multisecond pulses of intense hydrogen discharges. The properties of these films and the operating conditions of the plasma, source are described. Many ion beam and rf sources are available in the Fusion Energy Division of the Oak Ridge National Laboratory (ORNL). The potential application of these plasma sources to growing large, thick diamond films is discussed.

The Fusion Energy Division of the Oak Ridge National Laboratory (ORNL) in cooperation with the Princeton Plasma Physics Laboratory (PPPL) designed, constructed, and tested four high power neutral beam injectors for application on the Princeton Large Torus (PLT). This system employs a modified duoPIGatron ion source which has produced ion beams with parameters up to 70 A, 45 keV, and 500 msec. Nominal extraction parameters were 60-A, 40-keV, and 300-msec pulses, simultaneously. Neutral power up to 750 kW for 100 msec was calorimetrically measured on a simulated PLT target behind a PLT-sized aperture of 20 x 25 cm located at 4.10 m. Initial performance of these beam lines on PLT was near these parameters. Calorimetric measurements of beam power delivered to the PLT torus with a 3.65-m beam line length and with 100-msec full power pulses indicate a 10 to 15% reionization loss when the beam line pulse is synchronized to the pulsed torus magnetic fields. Data taken at ORNL are presented to show that this power loss is approximately equal to that calculated on drift tube pressure measurements taken without drift tube magnetic fields.

The design of a high brightness penning ion source is discussed. A cylindrical configuration (RINGATRON) is used. This is shown to improve ion extraction across the magnetic field. It also leads to enhanced production density. Comparisons of the ringatron configuration with the duoplasmatron and the planar penning discharge configuration are made. (AIP)

Six high power (40 keV--60 A) injection systems, four for PLT (Princeton Plasma Physics Laboratory) and two for ISX (Oak Ridge National Laboratory) tokamaks, have been developed, fabricated, and operated. Each injector delivers 750 kW (1000 kW) of H (D) neutral power to the tokamak plasma. An in-depth system parameter study has revealed unique features: high atomic yield (approximately 85%), improved ion optics due to a preacceleration technique, near steady-state operation (up to 500 msec), and a possible technique to control species yield. Routine operation includes high duty cycle (approximately 10%), long filament lifetime (several months), high arc efficiency, and the reliability necessary for application on a fusion device. The program status and injection parameters will be discussed.

The technology of acceleration of MeV energy negative ion beams is discussed with respect to embodiments proposed. These embodiments are capable of producing multi-ampere negative ion beams with an overall current density consistent with the beam emittance and application requirements. Included in these considerations for the various concepts are: (1) status of data base support, (2) options for dealing with the issues specific to negative ion acceleration, (3) current per channel and multiplexing senarios, (4) efficiency, (5) beam emittance, and (6) extent and limitations of present concept development.

This paper describes the development of a long-pulse positive ion source that has been designed to provide high brightness deuterium beams (divergence ≈ 0.25° rms, current density ≈ 0.15 A cm-2) of 40-45 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.

Utilization of a preacceleration potential to accelerate ions before they reach the emission aperture results in a substantial increase in the transmission efficiency. For an intense modified duoPIGatron focused multibeamlet (1799 apertures) 22‐cm‐diam ion source, the total transmission efficiency for beam power through an aperture 20×25 cm located 4.10 m downstream increased 30%. This result is in agreement with a previous solution to the appropriate two‐dimensional Poisson‐Vlasov equation for ions extracted from a plasma.

The foil-excitation method has been used to study the spectra of highly ionized oxygen. Wavelength measurements of transitions between S-, P- and D-states in heliumlike oxygen are reported and compared to theory and other experimental observations.

The beam-foil method has been used to study the spectra of highly ionized fluorine in the wavelength region ∼ 70–230A. Two new lines, assigned to the transitions 21,3Po-31,3S in FVIII, are reported.

The first observations of a number of optically inaccessible core-excited autoionizing states of lithium and sodium have been made. For example, the (1s2s 2 ) 2 S and (1s2p 2 ) 2 D states of Li have excitation energies of 56.31±0.03 and 61.04±0.03 eV, respectively.

Two PLT-injector-type duoPIGatron sources, modified further by shaping the beam-forming apertures, have been tested and experimented on a prototype 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 congruent to 910 kW of H/sup 0/ at an accelerator power of 42 kV and 61 A and congruent to 1020 kW of D/sup 0/ 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 +/ or D/sup +/); the distribution of beam power deposition along the beam line; ion species compositions; and background pressure behavior due to scraped-off beam particles.