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Collapse : The Shock Heating of a Plasma

Description: There have been numerous independent suggestions to use high speed shocks to heat deuterium gas to thermonuclear temperature (E. Teller, R.R. Wilson, H. Grad, W. Marshall)², and extensive experimental work in this field is being carried on by, e.g., Kolb³, and S. Janes⁴. Our own work in this field has been directed towards a fundamental understanding of the strong shock process in the limit of no particle collision, to find out if within this limit the ion heating following the passage of the shock is large enough to give rise to a thermonuclear reaction.
Date: March 7, 1958
Creator: Colgate, Stirling A. & Wright, R. E.
Partner: UNT Libraries Government Documents Department

Correlation of Neutral Beam Injection Parameters and Core B with Anomalous First-Wall Heating During QH-Mode

Description: Anomalous first-wall heating has been observed far from the divertor strike point during QH-mode in DIII-D, with measured heat flux comparable to that at the outer strike point. The data are consistent with deuterium ions of approximately the pedestal energy carrying the anomalous heat flux. Although an instability has not been identified that is correlated with the anomalous heat flux, two classes of behavior have been observed: one in which the anomalous heat flux depends linearly on core {beta}, and another class with no {beta}-dependence. The anomalous heat flux depends strongly on the injected beam energy of the non-tangentially-injected neutral beams but not that of the tangential beams.
Date: May 15, 2006
Creator: Lasnier, C; Burrell, K; deGrassie, J; Rhodes, T; VanZeeland, M & Watkins, J
Partner: UNT Libraries Government Documents Department

Volume Production of Negative Hydrogen and Deuterium Ions in aReflex-Type Ion Source

Description: The extraction of negative and positive hydrogen and deuterium ions from a reflex-type negative ion source has been investigated. Extracted positive and negative ion currents were measured as functions of the gas flow rate, the axial magnetic field, and the bias potential of the cylindrical wall of the arc-chamber. By biasing the cylindrical wall several volts negative relative to the anode, a maximum H{sup -} current of 9.7 mA(J{sup -} {approx_equal} 100 mA/cm{sup 2}) and D{sup -} current of 4.1 mA (J{sup -} {approx_equal} 42 mA/cm{sup 2})were obtained in steady state operation. This result shows a factor of two improvement over previous data. The total impurity negative ion content was less than 1%. When the source was arranged for positive ion extraction, a high proton ratio (90%) was observed. The extracted negative ion current was approximately as large as the positive ion current.
Date: January 1, 1986
Creator: Jimbo, K.; Ehlers, K.W.; Leung, K.N. & Pyle, R.V.
Partner: UNT Libraries Government Documents Department

The linear algebraic method for electron-molecule collisions

Description: In order to find numerical solutions to many problems in physics, chemistry and engineering it is necessary to place the equations of motion (classical or quantal) of the variables of dynamical interest on a discrete mesh. The formulation of scattering theory in quantum mechanics is no exception and leads to partial differential or integral equations which may only be solved on digital computers. Typical approaches introduce a numerical grid or basis set expansion of the scattering wavefunction in order to reduce `the problem to the solution of a set of algebraic equations. Often it is more convenient to deal with the scattering matrix or phase amplitude rather than the wavefunction but the essential features of the numerics are unchanged. In this section we will formulate the Linear Algebraic Method (LAM) for electron-atom/molecule scattering for a simple, one-dimensional radial potential. This will illustrate the basic approach and enable the uninitiated reader to follow the subsequent discussion of the general, multi-channel, electron-molecule formulation without undue difficulty. We begin by writing the Schroedinger equation for the s-wave scattering of a structureless particle by a short-range, local potential.
Date: September 1995
Creator: Collins, L. A. & Schneider, B. I.
Partner: UNT Libraries Government Documents Department

Deutron photodissociation in ultraperipheral relativistic heavyion on deutron collisions

Description: In ultraperipheral relativistic deuteron on heavy-ion collisions, a photon emitted from the heavy nucleus may dissociate the deuterium ion. We find deuterium breakup cross sections of 1.24 barns for deuterium-gold collisions at a center of mass energy of 200 GeV per nucleon, as studied at the Relativistic Heavy Ion Collider, and 2.35 barns for deuterium-lead collisions at a center of mass energy of 6.2 TeV, as proposed for the Large Hadron Collider. In the latter case, the cross section is as large as that of hadronic interactions. The estimated error is 5%. We discuss the use of this process as a luminosity monitor and a 'tag' for moderate impact parameter collisions.
Date: March 24, 2003
Creator: Klein, Spencer & Vogt, Ramona
Partner: UNT Libraries Government Documents Department

Characterization of deuterium beam operation on RHEPP-1 for future neutron generation applications.

Description: We investigate the potential for neutron generation using the 1 MeV RHEPP-1 intense pulsed ion beam facility at Sandia National Laboratories for a number of emerging applications. Among these are interrogation of cargo for detection of special nuclear materials (SNM). Ions from single-stage sources driven by pulsed power represent a potential source of significant neutron bursts. While a number of applications require higher ion energies (e.g. tens of MeV) than that provided by RHEPP-1, its ability to generate deuterium beams allow for neutron generation at and below 1 MeV. This report details the successful generation and characterization of deuterium ion beams, and their use in generating up to 3 x 10{sup 10} neutrons into 4{pi} per 5kA ion pulse.
Date: December 1, 2009
Creator: Schall, Michael (University of New Mexico, Albuquerque, NM); Cooper, Gary Wayne (University of New Mexico, Albuquerque, NM) & Renk, Timothy Jerome
Partner: UNT Libraries Government Documents Department

Sixty keV D/sup -/ beams using double charge-exchange system

Description: A D/sup -/ beam with current greater than 100 ma was accelerated to 60 kV. The beam, with pulse length 10 ms, was generated by charge-exchange in cesium vapor. The physics of generation, propagation at low energy, and acceleration is discussed.
Date: September 21, 1977
Creator: Hooper, E.B. Jr.; Anderson, O.A.; Orzechowski, T.J. & Poulsen, P.
Partner: UNT Libraries Government Documents Department

A Tutorial on Alpha-channelling

Description: One of the more ambitious uses of intense microwaves in tokamaks or in other magnetic confinement deuterium-tritium (DT) fusion devices would be to divert power from energetic alpha-particles to waves. This so-called "alpha-channelling" would be a large step towards achieving economical fusion power. The intense waves, amplified by the substantial free energy in the alpha-particles, damp on fuel ions, resulting in a hot ion mode, doubling the fusion power of the reactor at the same confined pressure. If the waves damp preferentially on electrons or ions traveling in one direction, current can be driven. This tutorial explains the key concepts and recent advances that lead us to believe in the plausibility of such an effect, at the same time showing how experiments to date give us a measure of confidence in both the simulations themselves, the underlying physical assumptions, and ultimately the reasonableness of the application of these ideas to alpha-channelling in a tokamak reactor.
Date: November 1, 1998
Creator: Fisch, N.J. & Herrmann, M.C.
Partner: UNT Libraries Government Documents Department

Production of negative hydrogen and deuterium ions in microwave-driven ion sources.

Description: The authors report progress they have made in the production of negative hydrogen and deuterium atomic ions in magnetically-confined microwave-driven (2.45 GHz) ion sources. The influence of source surface material, microwave power, source gas pressure and magnetic field configuration on the resulting ion current is discussed. Results strongly suggest that, at least in the source, vibrationally excited molecular hydrogen, the precursor to atomic negative ion production, is produced via a surface mechanism suggested by Hall et al. rather than via a gas phase reaction as is generally believed to be the case in most ion sources.
Date: September 11, 1998
Creator: Spence, D.
Partner: UNT Libraries Government Documents Department

Initial Study Comparing the Radiating Divertor Behavior in Single-Null and Double-Null Plasmas in DIII-D

Description: 'Puff and pump' radiating divertor scenarios [1,2] were applied to upper SN and DN H-mode plasmas. Under similar operating conditions, argon (Ar) accumulated in the main plasma of single-null (SN) plasmas more rapidly and reached a higher steady-state concentration when the B x {del}B ion drift direction was toward the divertor than when the B x {del}B ion drift direction was out of the divertor. The initial rate that Ar accumulated inside double-null (DN) plasmas was more than twice that of comparably-prepared SNs with the same B x {del}B direction. One way to reduce power loading at the divertor targets is to 'seed' the divertor plasma with impurities that radiatively reduce the conducted power. Studies have shown that the concentration of impurities in the divertor are increased by raising the flow of deuterium ions (D{sup +}) into the divertor by a combination of upstream deuterium gas puffing and active particle exhaust at the divertor targets, i.e., puff-and-pump. An enhanced D{sup +} particle flow toward the divertor targets exerts a frictional drag on impurities, and inhibits their escape from the divertor. A puff-and-pump approach using Ar as the impurity was successfully applied in recent DIII-D experiments to SN plasmas [3] while maintaining good H-mode performance. Studies on DIII-D and other tokamaks have shown that both the direction of the toroidal magnetic field B{sub T} and the degree of magnetic balance between divertors [i.e., the degree to which the plasma shape is considered SN or DN] are important factors in determining recycling and particle pumping [4,5]. It is unclear whether the favorable results of Ref. [3] can be extended to cases with different magnetic balance and/or B{sub T} direction. We show in this paper that reversing the direction of B{sub T} or altering the divertor magnetic balance does have an impact on ...
Date: June 27, 2007
Creator: Petrie, T; Brooks, N; Fenstermacher, M; Groth, M; Hyatt, A; Isler, R et al.
Partner: UNT Libraries Government Documents Department

Compatibility of the Radiating Divertor with High Performance Plasmas in DIII-D

Description: Excessive thermal power loading on the divertor structures presents a design difficulty for future-generation, high powered tokamaks. This difficulty may be mitigated by ''seeding'' the divertor with impurities which radiate a significant fraction of the power upstream of the divertor targets. For this ''radiating divertor'' concept to be practical, however, the confinement and stability of the plasma cannot be compromised by excessive leakage of the seeded impurities into the core plasma. One proposed way of reducing impurity influx is to enhance the directed scrape-off layer (SOL) flow of deuterium ions toward the divertor [1-5]. We report here on the successful application of the radiating divertor scenario to high performance plasma operation in a DIII-D ''hybrid'' H-mode regime. The ''hybrid'' regime [6,7] has many features in common with conventional ELMing H-mode regimes, such as high confinement, e.g., H{sub ITER89P} > 2, where H{sub ITER89P} is the energy confinement normalized to the 1989 ITER L-mode scaling [8]. The main difference is the absence of sawtooth activity in the hybrid. Argon was selected as the seeded impurity for this experiment because argon radiates effectively at both the divertor and pedestal temperatures found in DIII-D hybrid H-mode operation and has a relatively short ionization mean free path. Carbon is also present as the dominant intrinsic impurity in DIII-D discharges. The geometry of this experiment is shown in Fig. 1. A double-null cross-sectional shape was biased upward (dRsep = +1.0 cm). To increase the deuterium ion flow toward the divertor at the top of the vessel, deuterium gas was introduced near the bottom. Argon was injected directly into the private flux region (PFR) of the upper divertor. In-vessel pumping of deuterium and argon was done by cryopumps located in the two upper divertor plenums, shown in cross-hatching [9]. The upper divertor, which we hereafter will ...
Date: June 24, 2005
Creator: Petrie, T; Wade, M; Allen, S; Brooks, N; Fenstermacher, M; Ferron, J et al.
Partner: UNT Libraries Government Documents Department

Comprehensive Measurements and Modeling of SOL, and Core Plasma Fueling and Carbon Sources in DIII-D

Description: Plasma boundary modeling of low density, low confinement plasmas in DIII-D has been benchmarked against a comprehensive set of measurements and indicates that recycling of deuterium ions at the divertor targets, and chemical sputtering at the divertor target plates and walls, can explain the poloidal core fueling profile and core carbon density. Key measurements included the 2-D intensity distribution of deuterium neutral and low-charge state carbon emission in the divertor and around the midplane of the high-field scrape-off layer (SOL). Chemical sputtering plays an important role in producing carbon at the divertor targets and walls, and was found to be a prerequisite to reproduce the measured emission distribution.
Date: June 24, 2005
Creator: Groth, M.; Porter, G.; Bray, B.; Brooks, N.; Fenstermacher, M.; Groebner, R. et al.
Partner: UNT Libraries Government Documents Department

Determination of species yield of ion sources used for intense neutral-beam injection

Description: For efficient plasma heating, ion sources of neutral-beam injectors should be capable of producing ion beams with an atomic fraction of 90% or higher. Diagnostic techniques for quantitatively determining source species yield have been developed and evaluated. These include magnetic momentum analysis of the unneutralized ions passing through the neutralizer, energy analysis of the neutral beam by electrostatic separation of ions emanating from a stripping cell, and quantity vs implantation-depth analysis of hydrogen implanted into a crystal by SIMS technique. The operational features and advantages and disadvantages of each technique will be discussed. If the effects of beamlet optics, energy straggling in the accelerator, and neutralizer gas scattering are taken into account, the results of the measurements using the three techniques are shown to be mutually consistent within experimental error.
Date: January 1, 1982
Creator: Tsai, C.C.; Barnett, C.F.; Haselton, H.H.; Langley, R.A. & Stirling, W.L.
Partner: UNT Libraries Government Documents Department

The Argonne ACWL, a potential accelerator-based neutron source for BNCT

Description: The CWDD (Continuous Wave Deuterium Demonstrator) accelerator was designed to accelerate 80 mA cw of D{sup {minus}} to 7.5 MeV. Most of the hardware for the first 2 MeV was installed at Argonne and major subsystems had been commissioned when program funding from the Ballistic Missile Defense Organization ended in October 1993. Renamed the Argonne Continuous Wave Linac (ACWL), we are proposing to complete it to accelerate either deuterons to 2 MeV or protons to 33.5 MeV. Equipped with a beryllium or other light-element target, it would make a potent source of neutrons (on the order of 10{sup 13} n/s) for BNCT and/or neutron radiography. Project status and proposals for turning ACWL into a neutron source are reviewed, including the results of a computational study that was carried out to design a target/moderator to produce an epithermal neutron beam for BNCT.
Date: February 1, 1995
Creator: McMichael, G.E.; Yule, T.J. & Zhou, X.L.
Partner: UNT Libraries Government Documents Department

High flux compact neutron generators

Description: Compact high flux neutron generators are developed at the Lawrence Berkeley National Laboratory. The neutron production is based on D-D or D-T reaction. The deuterium or tritium ions are produced from plasma using either a 2 MHz or 13.56 MHz radio frequency (RF) discharge. RF-discharge yields high fraction of atomic species in the beam which enables higher neutron output. In the first tube design, the ion beam is formed using a multiple hole accelerator column. The beam is accelerated to energy of 80 keV by means of a three-electrode extraction system. The ion beam then impinges on a titanium target where either the 2.4 MeV D-D or 14 MeV D-T neutrons are generated. The MCNP computation code has predicted a neutron flux of {approximately}10{sup 11} n/s for the D-D reaction at beam intensity of 1.5 A at 150 kV. The neutron flux measurements of this tube design will be presented. Recently new compact high flux tubes are being developed which can be used for various applications. These tubes also utilize RF-discharge for plasma generation. The design of these tubes and the first measurements will be discussed in this presentation.
Date: June 15, 2001
Creator: Reijonen, J.; Lou, T.-P.; Tolmachoff, B.; Leung, K.-N.; Verbeke, J. & Vujic, J.
Partner: UNT Libraries Government Documents Department

Compact neutron source development at LBNL

Description: A compact neutron generator based on D-D or D-T fusion reactions is being developed at the Lawrence Berkeley National Laboratory. The deuterium or tritium ions are produced in a radio-frequency (RF) driven multicusp plasma source. Seven beamlets are extracted and are accelerated to energy of 100 keV by means of a three-electrode electrostatic accelerator column. The ion beam then impinges on a titanium coated copper target where either the 2.4 MeV D-D or 14 MeV D-T neutrons are generated by fusion reaction. The development of the neutron tube is divided into three phases. First, the accelerator column is operated at hydrogen beam intensity of 15 mA. Second phase consists of deuterium beam runs at pulsed, low duty cycle 150 mA operation. The third phase consists of deuterium or tritium operation at 1.5 A beam current. Phase one is completed and the results of hydrogen beam testing are discussed. Low duty cycle 150 mA deuterium operation is being investigated. Neutron flux will be measured. Finally the phase three operation and the advance neutron generator designs are described.
Date: July 25, 2001
Creator: Reijonen, Jani; Lou, Tak Pui; Tolmachoff, Bryan & Leung, K.N.
Partner: UNT Libraries Government Documents Department

Carbon influx in He and D plasmas in DIII-D

Description: Differences in the carbon behavior between He and D plasmas during VH-mode, L-mode and L-mode with excess gas puffing are reported and inferences on the importance of the various carbon sources during these modes of operation are discussed. During a VH-mode phase, VUV and visible charge exchange spectroscopy indicates that for both He and D operation the carbon behavior is very similar. In the edge plasma, carbon build up is quite rapid, and the carbon influx represents a large fraction of the total plasma density increase until the termination of the VH phase. During cold divertor operation induced by puffing the primary fueling gas, D and He discharges show a difference in the carbon behavior. The core carbon density is seen to be approximately constant during a D discharge as it transitions from an attached to a cold divertor. However in a He discharge, the core carbon density disappears soon after the cold divertor transition. Arguments are made that the primary carbon source in the ELM free H-mode period is physical sputtering by ion impact at the divertor strike point. In L-mode, both attached and cold divertor, the primary source is from the divertor region and two possibilities for this source are chemical sputtering or charge neutral sputtering. Existing data supports charge exchange neutrals as dominant.
Date: July 1998
Creator: West, W.P.; Brooks, N.H. & Fenstermacher, M.E.
Partner: UNT Libraries Government Documents Department

Improved method for the production of atomic ion species from plasma ion sources

Description: A technique to enhance the yield of neutral atomic and ionic species (H{sup +}, D{sup +}, O{sup +}, N{sup +}, etc.) from plasmas. The technique involves the addition of catalyzing agents to the ion discharge. Effective catalysts include H{sub 2}O, O{sub 2}, and SF{sub 6}, among others, with the most effective being water (H{sub 2}O). This technique has been developed at Argonne National Laboratory, where microwave produced beams consisting essentially of 100% atomic neutral species (H) have been generated, and ion beams of close to 100% purity have been generated.
Date: December 31, 1996
Creator: Spence, D. & Lykke, K.
Partner: UNT Libraries Government Documents Department

Calibration of a direct nuclear activation diagnostic which uses boron nitride to measure energetic deuterium ions

Description: A direct nuclear activation diagnostic for the measurement of the kinetic energy of deuterium ions in the energy range of 1 to 3 MeV has been successfully developed. This diagnostic is based on the fact that the ratio of two different thick target yields which are generated by the same incident ion species can be a sensitive function of incident ion energy. Targets for this diagnostic are made of {alpha}-boron nitride (BN) and use the two reactions: {sup 10}B(d,n){sup 11}C({beta}+) and {sup 14}N(d,n){sup 15}O({beta}+). As long as the BN material matrix remains constant, the ratio of thick target yields depends only on the deuterium ion energy and is independent of ion fluence and detector efficiency. Calibration of the diagnostic was accomplished by irradiating BN targets with deuterium beams of known ion kinetic energy and fluence. The calibrated diagnostic was then fielded to measure the voltage in a Plasma Opening Switch (POS). Electrical measurements of the POS voltage and the voltage inferred from the BN nuclear activation diagnostic were in good agreement.
Date: July 1998
Creator: Cooper, G. W.; Chambers, G. D.; Savage, M. E.; Ruiz, C. L. & Schmidlapp, F. A.
Partner: UNT Libraries Government Documents Department

Oxide cathode lifetime improvements at RTNS-II

Description: Results are reported for an ongoing effort to optimize D/sup +/ beam production by the MATS-III ion source used at the RTNS-II. The oxide cathode assembly originally designed for lower power operation has been modified and redesigned for higher electron current yield, longer life and serviceability. A factor of 2.5 has been gained in cathode lifetime due to these changes. The details of the changes and results and benefits in operation and performance are given. In addition, the technique used for manufacture of the filament is described.
Date: September 29, 1986
Creator: Massoletti, D.J.
Partner: UNT Libraries Government Documents Department

The Safety and Tritium Applied Research (STAR) Facility: Status-2004*

Description: The purpose of this paper is to present the current status of the development of the Safety and Tritium Applied Research (STAR) Facility at the Idaho National Engineering and Environmental Laboratory (INEEL). Designated a National User Facility by the US DOE, the primary mission of STAR is to provide laboratory infrastructure to study tritium science and technology issues associated with the development of safe and environmentally friendly fusion energy. Both tritium and non-tritium fusion safety research is pursued along three key thrust areas: (1) plasma-material interactions of plasma-facing component (PFC) materials exposed to energetic tritium and deuterium ions, (2) fusion safety concerns related to PFC material chemical reactivity and dust/debris generation, activation product mobilization, and tritium behavior in fusion systems, and (3) molten salts and fusion liquids for tritium breeder and coolant applications. STAR comprises a multi-room complex with operations segregated to permit both tritium and non-tritium activities in separately ventilated rooms. Tritium inventory in STAR is limited to 15,000 Ci to maintain its classification as a Radiological Facility. Experiments with tritium are typically conducted in glovebox environments. Key components of the tritium infrastructure have been installed and tested. This includes the following subsystems: (1) a tritium Storage and Assay System (SAS) that uses two 50-g depleted uranium beds for tritium storage and PVT/beta-scintillation analyses for tritium accountability measurements, (2) a Tritium Cleanup System (TCS) that uses catalytic oxidation and molecular sieve water absorption to remove tritiated species from glovebox atmosphere gases and gaseous effluents from experiment and process systems, and (3) tritium monitoring instrumentation for room air, glovebox atmosphere and stack effluent tritium concentration measurements. Integration of the tritium infrastructure subsystems with the experimental and laboratory process systems is planned for early in 2004. Following an operational readiness review, tritium operations will be initiated in the summer of 2004. ...
Date: September 1, 2004
Creator: Anderl, R. A.; Longhurst, G. R.; Pawelko, R. J.; Sharpe, J. P.; Schuetz, S. T. & Petti, D. A.
Partner: UNT Libraries Government Documents Department