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Technology of neutral-beam injection based on positive-ion sources

Description: Advances made in each of the following areas are summarized: (1) long pulse plasma sources, (2) the arc discharge, (3) the atomic species, (4) impurities, (5) accelerator development, (6) beam line components, and (7) the role of positive-ion-based injection systems for reactor-size devices. (MOW)
Date: January 1, 1983
Creator: Menon, M.M.
Partner: UNT Libraries Government Documents Department

Status and trends in the development and application of positive-ion-based neutral injectors

Description: The present status of the technology of positive-ion-based neutral injectors is examined with particular reference to the Oak Ridge National Laboratory neutral beam development program. It is shown that the development and application of multi-megawatt neutral beams have been quite successful. Injector parameters that have been utilized and those that are planned to be utilized in various confinement devices are examined. Development needs for the upcoming applications are shown to be primarily in the area of extending the beam pulse length to several seconds. The accomplishment of this goal will be a major step towards realizing a reactor-grade injector if the beam energy requirement for such an application is about 150 keV or less.
Date: January 1, 1981
Creator: Menon, M.M.
Partner: UNT Libraries Government Documents Department

Investigation on the utilization of coal fly ash as amendment to compost for vegetation in acid soil

Description: Application of fly ash-amended composts as manure enhances the crop yield of certain plants like corn, sorghum, collard and mustard greens. Organic compost made out of grass and leaves (home-made) is better than the commercial composts for amendment with fly ash. A 20--40% fly ash in the amended compost and a soil to ash-amended compost ratio of 3:1 are recommended for making bed for plantation. Organic compost mixed with fly ash, due to reduced porosity, will help the bed to retain water and conserve water supply to plants. Organic compost will release to the manure additional quantities of N, P, and S that are not substantially available in fly ash. It appears that chemical reaction and/or mineralization occurs during composting of fly ash with organic manure to release more N, P, K and S to the system. Potassium is more elevated in all plants grown in potted soil treated with fly ash-amended compost than in those grown in soil or soil treated with organic manure. Contrary to expectation Ca in fly ash is not effectively used by plants as the latter treated with ash- amended compost is not rich in Ca. This suggests that Ca may be tied up as insoluble CaSO{sub 4} in the manure so that it may not be bioavailable to the plant. Uptake of boron by bean, bell pepper and egg plant is considerably higher than that absorbed by corn, sorghum and greens resulting in poor yield for the former.
Date: August 1, 1991
Creator: Menon, M.P.
Partner: UNT Libraries Government Documents Department

Energy dissipation on ion-accelerator grids during high-voltage breakdown

Description: The effects of stored energy in the system capacitance across the accelerator grids during high voltage vacuum breakdown are examined. Measurements were made of the current flow and the energy deposition on the grids during breakdown. It is shown that only a portion (less than or equal to 40 J) of the total stored energy (congruent to 100 J) is actually dissipated on the grids. Most of the energy is released during the formation phase of the vacuum arc and is deposited primarily on the most positive grid. Certain abnormal situations led to energy depositions of about 200 J on the grid, but the ion accelerator endured them without exhibiting any deterioration in performance.
Date: January 1, 1981
Creator: Menon, M.M. & Ponte, N.S.
Partner: UNT Libraries Government Documents Department

Investigation on the utilization of coal fly ash as amendment to compost for vegetation in acid soil. Technical terminal report

Description: Application of fly ash-amended composts as manure enhances the crop yield of certain plants like corn, sorghum, collard and mustard greens. Organic compost made out of grass and leaves (home-made) is better than the commercial composts for amendment with fly ash. A 20--40% fly ash in the amended compost and a soil to ash-amended compost ratio of 3:1 are recommended for making bed for plantation. Organic compost mixed with fly ash, due to reduced porosity, will help the bed to retain water and conserve water supply to plants. Organic compost will release to the manure additional quantities of N, P, and S that are not substantially available in fly ash. It appears that chemical reaction and/or mineralization occurs during composting of fly ash with organic manure to release more N, P, K and S to the system. Potassium is more elevated in all plants grown in potted soil treated with fly ash-amended compost than in those grown in soil or soil treated with organic manure. Contrary to expectation Ca in fly ash is not effectively used by plants as the latter treated with ash- amended compost is not rich in Ca. This suggests that Ca may be tied up as insoluble CaSO{sub 4} in the manure so that it may not be bioavailable to the plant. Uptake of boron by bean, bell pepper and egg plant is considerably higher than that absorbed by corn, sorghum and greens resulting in poor yield for the former.
Date: August 1, 1991
Creator: Menon, M. P.
Partner: UNT Libraries Government Documents Department

A calorimeter for measuring the neutral beam power reaching the plasma

Description: A calorimeter has been designed to measure the neutral beam power reaching the Advanced Toroidal Facility (ATF) plasma. The high-heat-flux surface of this calorimeter is made of an array of graphite tiles. The calorimeter, which will be located in the adapter section between the ATF vacuum vessel and the beam line, is retractable so that it can be moved away from the plasma without opening the vacuum vessel during normal ATF operation. Two rows of thermocouples mounted perpendicular to each other allow determination of the beam profile. This paper presents the details of the design and fabrication of the calorimeter. 5 refs., 6 figs.
Date: January 1, 1987
Creator: Menon, M.M.; Edmonds, P.H. & Hahs, C.L.
Partner: UNT Libraries Government Documents Department

ORNL 150 keV neutral beam test facility

Description: The 150 keV neutral beam test facility provides for the testing and development of neutral beam injectors and beam systems of the class that will be needed for the Tokamak Fusion Test Reactor (TFTR) and The Next Step (TNS). The test facility can simulate a complete beam line injection system and can provide a wide range of experimental operating conditions. Herein is offered a general description of the facility's capabilities and a discussion of present system performance.
Date: January 1, 1977
Creator: Gardner, W.L.; Kim, J.; Menon, M.M. & Schilling, G.
Partner: UNT Libraries Government Documents Department

PLT neutral beam injection systems

Description: A brief description of the Princeton Large Torus (PLT) neutral beam injection system is given and its performance characteristics are outlined. A detailed operational procedure is included, as are some tips on troubleshooting. Proper operation of the source is shown to be a crucial factor in system performance.
Date: January 1, 1979
Creator: Menon, M.M.; Barber, G.C. & Blue, C.W.
Partner: UNT Libraries Government Documents Department

ATF neutral beam injection system

Description: The Advanced Toroidal Facility is a stellarator torsatron being built at Oak Ridge National Laboratory to investigate improved plasma confinement schemes. Plasmas heating will be carried out predominantly by means of neutral beam injection. This paper describes the basic parameters of the injection system. Numerical calculations were done to optimize the aiming of the injectors. The results of these calculations and their implications on the neutral power to the machine are elaborated. The effects of improving the beam optics and altering the focal length on the power transmitted to the plasma are discussed.
Date: January 1, 1985
Creator: Menon, M.M.; Morris, R.N. & Edmonds, P.H.
Partner: UNT Libraries Government Documents Department

Radiation effects on optical components of a laser radar sensor designed for remote metrology in ITER

Description: A frequency modulated laser radar is being developed for in-vessel metrology and viewing of plasma-facing surfaces. Some optical components of this sensor must withstand intense gamma radiation (3 {times} 10{sup 6} rad/h) during operation. The authors have tested the effect of radiation on a silica core polarization maintaining optical fiber and on TeO{sub 2} crystals at doses up to {approximately} 10{sup 9} rad. Additional tests are planned for evaluating the performance of a complete acousto-optic (AO) scanning device. The progress made in these tests is also described.
Date: September 1, 1997
Creator: Menon, M.M.; Grann, E.B. & Slotwinski, A.
Partner: UNT Libraries Government Documents Department

Particle exhaust schemes in the DIII-D advanced divertor configuration

Description: For density control in long-pulse operation, the open divertor on the DIII-D tokamak will be equipped with a baffled chamber and a pumping system. The throat of the baffle chamber is sized to provide optimal pumping for the typical plasma equilibrium configuration. Severe limitations on the toroidal conductance of this baffle chamber require the use of in-vessel pumping to achieve the desired particle exhaust of about 25 Torr{center dot}l/s. Two separate pumping schemes are considered: an array of titanium getter modules based on the design developed by the Tore Supra team and a cryocondensation pump. The merits and demerits of each scheme are analyzed, and the design considerations introduced by the tokamak environment are brought out. 3 refs., 5 figs.
Date: January 1, 1989
Creator: Menon, M.M. & Mioduszewski, P.K.
Partner: UNT Libraries Government Documents Department

A Remotely Deployed Laser System for Viewing/Metrology

Description: A metrology system is being developed for in-vessel inspection of present day experimental, and next generation fusion reactors. It requires accurate measuring capability to verify sub-millimeter alignment of plasma-facing components in the reactor vessel. A metrology system capable of achieving such accuracy for next generation reactors must be compatible with the vessel environment of high gamma radiation, high vacuum, elevated temperature, and magnetic field. This environment requires that the system must be remotely deployed. A coherent, frequency modulated laser radar system that is capable of correcting for environmental vibration meets these requirements. The metrologyhiewing system consists of a compact laser transceiver optics module which is linked through fiber optics to the laser source and imaging units, that are located outside of the harsh environment. The deployment mechanism configured for a next generation reactor was telescopic-mast positioning system. This paper identifies the requirements for the metrology/viewing system having precision ranging and surface mapping capability, and discusses the results of various environmental tests.
Date: April 25, 1999
Creator: Barry, R.E.; Herndon, J.N.; Menon, M.M. & Spampinato, P.T.
Partner: UNT Libraries Government Documents Department

Remote Metrology, Mapping, and Motion Sensing of Plasma Facing Components Using FM Coherent Laser Radar

Description: Metrology inside a D/T burning fusion reactor must necessarily be conducted remotely since the in-vessel environment would be highly radioactive due to neutron activation of the torus walls. A technique based on frequency modulated coherent laser radar (FM CLR) for such remote metrology is described. Since the FM CLR relies on frequency shift to measure distances, the results are largely insensitive to surface reflectance characteristics. Results of measurements in TFTR and NSTX fusion devices using a prototype FM CLR unit, capable of remotely measuring distances (range) up to 22 m with better than 0.1-mm precision, are provided. These results illustrate that the FM CLR can be used for precision remote metrology as well as viewing. It is also shown that by conducting Doppler corrected range measurements using the CLR, the motion of objects can be tracked. Thus, the FM CLR has the potential to remotely measure the motion of plasma facing components (PFCs) during plasma disruptions.
Date: September 11, 2000
Creator: Menon, M.M.; Barry, R.E.; Slotwinsky, A.; Kugel, H.W. & Skinner, C.H.
Partner: UNT Libraries Government Documents Department

A coherent FM laser radar based system for remote metrology in ITER

Description: The plasma facing surfaces in ITER must be aligned to millimeter accuracy with respect to the magnetic flux surfaces to prevent impurity influx into the plasma and to avoid component damage. Checking of in-vessel component alignment during initial assembly, operation, and subsequent maintenance is anticipated. A fully remote metrology system is necessary, particularly since major remote operations such as shield blanket exchange and divertor cassette replacement are planned. The metrology system must be compatible with the ITER in-vessel environment of high gamma radiation ({approximately} 10{sup 6} R/hr), super-clean ultra-high-vacuum ({approximately} 10{sup {minus}8} Torr), and elevated temperature ({approximately}200 C). A fast scanning rate is required since the plasma facing surface in ITER is very large ({approximately} 1,500 m{sup 2}). A coherent FM laser radar based metrology system, developed by Coleman Research Corporation, is being adopted to accomplish this task. Conceptually, this metrology system consists of a compact (few cm{sup 3}) remotely deployed laser transceiver optics module, linked through fiber optics to the laser source and imaging units that are located outside the biological shield. Range measurements conducted on a variety of surfaces using the system have yielded sub-millimeter accuracy. Therefore, the technique will easily meet the precision requirement for the ITER application. Computer simulations have been carried out to determine the optimum number of units required for complete mapping of the plasma facing surfaces. Most in-vessel components of the system appear to be radiation hardenable and vacuum compatible. Details of the system and developments required to make it fully compatible for ITER metrology application will be elaborated.
Date: December 31, 1995
Creator: Barry, R.E.; Burgess, T.W.; Menon, M.M.; Slotwinski, A. & Sebastian, R.
Partner: UNT Libraries Government Documents Department

dc plasma generator development for neutral-beam injectors

Description: Rectangular plasma generators are being developed with the capability of producing hydrogen ion beams of 60 to 100 A. Using single and double electron feed configurations of the duoPIGatron type, these generators have been operated at arc levels of 1200 A for pulse lengths of > 30 s. The plasma density and uniformity are sufficient for extracting approx. 60-A hydrogen ions using a 13 x 43 cm accelerator and approx. 100 A with an 18 x 48 cm accelerator.
Date: January 1, 1981
Creator: Tsai, C.C.; Schechter, D.E.; Haselton, H.H.; Menon, M.M.; Ryan, P.M. & Stirling, W.L.
Partner: UNT Libraries Government Documents Department

Advanced design of positive-ion sources for neutral-beam applications

Description: The APIS ion source is being developed to meet a goal of producing ion beams of less than or equal to 200 keV, 100 A, with 10-30-s pulse lengths. In a continuing effort to advance the state of the art and to produce long pulse ion beams, APIS ion sources with grid dimensions of 10 x 25 cm, 13 x 43 cm, and 16 x 48 cm are being developed. In the past year, the 10- x 25-cm ion source has been operated to produce ion beams in excess of 100 keV for many seconds pulse length. An advanced design concept is being pursued with the primary objectives to improve radiation protection, reduce fabrication costs, and simplify maintenance. The source magnetic sheild will be designed as a vacuum enclosure to house all source components. The electrical insulation requirements of energy recovery are also considered. Because of the frequent maintenance requirements, the electron emitter assembly will be designed with a remote handling capability. A new accelerator design which incorporates the necessary neutron shielding and associated steering gimbal system is also described.
Date: January 1, 1982
Creator: Marguerat, E.F.; Haselton, H.H.; Menon, M.M.; Schechter, D.E.; Stirling, W.L. & Tsai, C.C.
Partner: UNT Libraries Government Documents Department

Particle exhaust modeling for the collaborative DIII-D Advanced Divertor Program

Description: A principal objective of the collaborative DIII-D Divertor Program (ADP) is to achieve density control in H-mode discharges with edge biasing and with continuous particle exhaust at a rate determined by the external fueling sources (typically 20 Torr{center dot}L/s). The divertor baffle-bias ring system has been optimized for pumping speeds {approx}50,000 L/s with the neutral transport code DEGAS. With an entrance slot conductance of 50,000 L/s, a pumping speed of the same order is required to remove half of the {approx}40 Torr{center dot}L/s that enters the baffle chamber for typical H-mode discharges. Increasing the exhaust fraction with higher pumping speed is self-limiting, owing to the attendant reduction of the recycling flux. The effects of pumping on the plasma core, scrape-off layer (SOL), and divertor have been estimated with a model that self-consistently couples the transport in these regions. The required {approx}50,000 L/s pumping speed can be achieved with either titanium getter pumps or cryopumps. Evaluation of both systems has led to the conclusion that cryopumps will be more compatible with the environment of the DIII-D divertor. 8 refs., 7 figs.
Date: January 1, 1990
Creator: Mioduszewski, P.K.; Owen, L.W. & Menon, M.M. Hogan, J.T.
Partner: UNT Libraries Government Documents Department

Development and testing of the ORNL/PLT neutral beam lines for the Princeton Large Torus

Description: Four neutral beam lines have been designed, constructed, and tested by the Oak Ridge National Laboratory (ORNL) in cooperation with the Princeton Plasma Physics Laboratory (PPPL) for application on the Princeton Large Torus (PLT) at PPPL. Two neutral beam lines are counterinjectors and two are coinjectors for a total neutral beam power of greater than 3 MW at 40 keV and up to 300 msec. Each beam line utilizes a 40-kV times 60-A modified duoPIGatron ion source with a close-coupled, 1.0-m long gas cell. Species ratios produced by the ion source are 84:13:3:E: E/2:E/3 for H/sup 0/ components delivered to the torus. The arc efficiency is less than 1 kW of arc power per ampere of beam current. Gas efficiency is approximately 50 percent with a total gas throughput of approximately 20 T-l/sec including supplemental gas to the gas cell. Two LHe cryocondensation pumps are used, one in the ion source tank with a speed of approximately 400,000 l/sec and the other in the drift tube with a speed of approximately 20,000 l/sec. The first beam line has been operated on PLT and has delivered 500 kW to the tokamak calorimeter for 150 msec. Initial heating results at 400 kW indicate an increase in T/sub i/, the central ion temperature, from 0.8 keV to approximately 1.5 keV.
Date: January 1, 1977
Creator: Dagenhart, W.K.; Gardner, W.L.; Haselton, H.H.; Menon, M.M.; Schechter, D.E.; Stirling, W.L. et al.
Partner: UNT Libraries Government Documents Department

A laser scanning system for metrology and viewing in ITER

Description: The construction and operation of a next-generation fusion reactor will require metrology to achieve and verify precise alignment of plasma-facing components and inspection in the reactor vessel. The system must be compatible with the vessel environment of high gamma radiation (10{sup 4} Gy/h), ultra-high-vacuum (10{sup {minus}8} torr), and elevated temperature (200 C). The high radiation requires that the system be remotely deployed. A coherent frequency modulated laser radar-based system will be integrated with a remotely operated deployment mechanism to meet these requirements. The metrology/viewing system consists of a compact laser transceiver optics module which is linked through fiber optics to the laser source and imaging units that are located outside of a biological shield. The deployment mechanism will be a mast-like positioning system. Radiation-damage tests will be conducted on critical sensor components at Oak Ridge National Laboratory to determine threshold damage levels and effects on data transmission. This paper identifies the requirements for International Thermonuclear Experimental Reactor metrology and viewing and describes a remotely operated precision ranging and surface mapping system.
Date: May 1, 1996
Creator: Spampinato, P.T.; Barry, R.E.; Menon, M.M.; Herndon, J.N.; Dagher, M.A. & Maslakowski, J.E.
Partner: UNT Libraries Government Documents Department

Metrology/viewing system for next generation fusion reactors

Description: Next generation fusion reactors require accurate measuring systems to verify sub-millimeter alignment of plasma-facing components in the reactor vessel. A metrology system capable of achieving such accuracy must be compatible with the vessel environment of high gamma radiation, high vacuum, elevated temperature, and magnetic field. This environment requires that the system must be remotely deployed. A coherent, frequency modulated laser radar system is being integrated with a remotely operated deployment system to meet these requirements. The metrology/viewing system consists of a compact laser transceiver optics module which is linked through fiber optics to the laser source and imaging units that are located outside of the harsh environment. The deployment mechanism is a telescopic-mast positioning system. This paper identifies the requirements for the International Thermonuclear Experimental Reactor metrology and viewing system, and describes a remotely operated precision ranging and surface mapping system.
Date: February 1, 1997
Creator: Spampinato, P.T.; Barry, R.E.; Chesser, J.B.; Menon, M.M. & Dagher, M.A.
Partner: UNT Libraries Government Documents Department

Precision metrology of NSTX surfaces using coherent laser radar ranging

Description: A frequency modulated Coherent Laser Radar ranging diagnostic is being used on the National Spherical Torus Experiment (NSTX) for precision metrology. The distance (range) between the 1.5 {micro}m laser source and the target is measured by the shift in frequency of the linearly modulated beam reflected off the target. The range can be measured to a precision of < 100{micro}m at distances of up to 22 meters. A description is given of the geometry and procedure for measuring NSTX interior and exterior surfaces during open vessel conditions, and the results of measurements are elaborated.
Date: July 13, 2000
Creator: Kugel, H.W.; Loesser, D.; Roquemore, A. L.; Menon, M. M. & Barry, R. E.
Partner: UNT Libraries Government Documents Department