Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Improved core fueling with high field side pellet injection in the DIII-D tokamak : The 41st annual meeting of the division of plasma physics of the american physical society (2000)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 7 (2000), S. 1878-1885 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The capability to inject deuterium pellets from the magnetic high field side (HFS) has been added to the DIII-D tokamak [J. L. Luxon and L. G. Davis, Fusion Technol. 8, 441 (1985)]. It is observed that pellets injected from the HFS lead to deeper mass deposition than identical pellets injected from the outside midplane, in spite of a factor of 4 lower pellet speed. HFS injected pellets have been used to generate peaked density profile plasmas [peaking factor (ne(0)/〈ne〉) in excess of 3] that develop internal transport barriers when centrally heated with neutral beam injection. The transport barriers are formed in conditions where Te∼Ti and q(0) is above unity. The peaked density profiles, characteristic of the internal transport barrier, persist for several energy confinement times. The pellets are also used to investigate transport barrier physics and modify plasma edge conditions. Transitions from L- to H-mode have been triggered by pellets, effectively lowering the H-mode threshold power by 2.4 MW. Pellets injected into H-mode plasmas are found to trigger edge localized modes (ELMs). ELMs triggered from the low field side (LFS) outside midplane injected pellets are of significantly longer duration than from HFS injected pellets. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.874011
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    A combined microwave cavity and photographic diagnostic for high-speed projectiles (1990)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 2102-2105 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A combined microwave cavity and photographic diagnostic for high-speed projectiles has been developed. The diagnostic allows consistent determination of projectile mass and shape and serves as one fiducial mark for a speed measurement. The 3.219-GHz cavity has been used for experiments with both frozen deuterium and plastic pellets traveling at speeds from 1500–4500 m/s.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1141374
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Repetitive two-stage light gas gun for high-speed pellet injection (1991)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 62 (1991), S. 1978-1989 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A repetitive two-stage light gas gun for high-speed pellet injection has been developed at Oak Ridge National Laboratory. In general, applications of the two-stage light gas gun have been limited to only single shots, with a finite time (at least minutes) needed for recovery and preparation for the next shot. The new device overcomes problems associated with repetitive operation, including rapidly evacuating the propellant gases, reloading the gun breech with a new projectile, returning the piston to its initial position, and refilling the first- and second-stage gas volumes to the appropriate pressure levels. In addition, some components are subjected to and must survive severe operating conditions, which include rapid cycling to high pressures and temperatures (up to thousands of bars and thousands of kelvins) and significant mechanical shocks. Small plastic projectiles (4 mm nominal size) and helium gas have been used in the prototype device, which was equipped with a 1-m-long pump tube and a 1-m-long gun barrel, to demonstrate repetitive operation (up to 1 Hz) at relatively high pellet velocities (up to 3000 m/s). The highest experimental velocity is twice that available from conventional repeating single-stage pneumatic injectors that accelerate frozen pellets of hydrogen isotopes and are now used to fuel magnetically confined plasmas for controlled thermonuclear fusion research. Also, the pellet test repetition rate of 1 Hz is relevant for fueling applications on future large fusion research devices. The equipment is described, and experimental results are presented and compared with calculated results from gas dynamics models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142402
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Extruder system for high-throughput/steady-state hydrogen ice supply and application for pellet fueling of reactor-scale fusion experiments (1998)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 69 (1998), S. 4012-4013 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Pellet injection systems for the next-generation fusion devices, such as the proposed International Thermonuclear Experimental Reactor (ITER), will require feed systems capable of providing a continuous supply of hydrogen ice at high throughputs. A straightforward concept in which multiple extruder units operate in tandem has been under development at the Oak Ridge National Laboratory. A prototype with three large-volume extruder units has been fabricated and tested in the laboratory. In experiments, it was found that each extruder could provide volumetric ice flow rates of up to ∼1.3 cm3/s (for ∼10 s), which is sufficient for fueling fusion reactors at the gigawatt power level. With the three extruders of the prototype operating in sequence, a steady rate of ∼0.33 cm3/s was maintained for a duration of 1 h. Even steady-state rates approaching the full ITER design value (∼1 cm3/s) may be feasible with the prototype. However, additional extruder units (1–3) would facilitate operations at the higher throughputs and reduce the duty cycle of each unit. The prototype can easily accommodate steady-state pellet fueling of present large tokamaks or other near-term plasma experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149216
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    High-speed repeating hydrogen pellet injector for long-pulse magnetic confinement fusion experiments (1996)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 67 (1996), S. 1834-1841 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The projected fueling requirements of future magnetic confinement fusion devices [e.g., the International Thermonuclear Experimental Reactor (ITER)] indicate the need for a flexible plasma fueling capability, including both gas puffing and low- and high-speed pellet injection. Conventional injectors, based on single-stage pneumatic guns or centrifuges, can reliably provide frozen pellets (1- to 6-mm-diam sizes) at speeds up to 1.3 km/s and at suitable repetition rates (1 to 10 Hz or greater). Injectors based on two-stage pneumatic guns and "in situ'' condensation of hydrogen pellets can reliably achieve velocities over 3 km/s; however, they are not suitable for long-pulse repetitive operations. An experiment in collaboration between Oak Ridge National Laboratory (ORNL) and ENEA Frascati is under way to demonstrate the feasibility of a high-speed ((approximately-greater-than)2 km/s) repeating (∼1 Hz) pneumatic pellet injector for long-pulse operation. A test facility has been assembled at ORNL, combining a Frascati repeating two-stage light-gas gun and an ORNL deuterium extruder, equipped with a pellet chambering mechanism/gun barrel assembly. The main issues to be investigated were the strength of extruded deuterium ice as opposed to that produced by in situ condensation in pipe guns (hence the highest acceleration which can be given to the pellet without fracturing it), and the maximum repetition rate at which the system can operate without degradation in performance. Pellet velocities of up to 2.55 km/s have been achieved in joint experiments at ORNL. A new pressure tailoring valve was developed by the Frascati group for this application and proved to be a crucial component for good performance. Tests carried out in repeating mode, at frequencies of 0.2–0.5 Hz and speeds up to 2.2 km/s, indicate no significant degradation in performance with increasing repetition rate. Some preliminary tests using 3.7 mm pellets gave very encouraging results. The equipment and the experimental results are described in this article. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1146988
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Acceleration of neon pellets to high speeds for fusion applications (1996)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 67 (1996), S. 837-839 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The injection of impurity pellets into the plasmas of tokamak fusion reactors has been proposed as a technique to lessen the deleterious effects of plasma disruptions. Equipment and techniques that were previously developed for pneumatic hydrogen pellet injection systems and used for plasma fueling applications were employed for a limited experimental study with neon pellets. Isotopic hydrogen pellets doped with neon have previously been used for injection into fusion plasmas to study impurity particle transport, and pure neon pellets are applicable for disruption studies. Using a repeating pneumatic injector in the laboratory, it was found that the formation and acceleration of 2.7-mm-diam neon pellets were relatively straightforward; reliable operation was demonstrated with both a single- and a two-stage light gas gun, including velocities of ∼700 m/s with a single-stage injector and up to 1740 m/s with a two-stage injector. Based on the operating sequences and successful tests demonstrated in the laboratory experiments, a three-barrel repeating pneumatic injector installed on the DIII-D tokamak was equipped with the necessary components for neon operation and has been used in initial disruption experiments with 1.8-mm-diam neon pellets. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1146819
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Small-bore (1.8-mm), high-firing-rate (10-Hz) version of a repeating pneumatic hydrogen pellet injector (1995)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 2736-2737 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Repeating pneumatic pellet injectors developed at the Oak Ridge National Laboratory (ORNL) were used for plasma fueling experiments on the Tokamak Fusion Test Reactor (TFTR) and the Joint European Torus (JET). For plasma fueling on the DIII–D tokamak, a small-bore (1.8-mm) injector has been developed and tested in the laboratory at pellet rates of up to 10 Hz and speeds of ≤1 km/s (for pulse lengths of up to 15 s). This performance represents the smallest pellet size and highest repetition rate demonstrated with an ORNL repeating pneumatic pellet injector. The design has been incorporated in the three-barrel injector that was previously used on JET; the injection system, equipped with nominal pellet sizes of 1.8-, 2.7-, and 4.0-mm diameter, has been installed on DIII–D and will be used in future plasma fueling experiments. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1145620
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Pellet injection technology (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1679-1698 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: During the last 10 to 15 years, significant progress has been made worldwide in the area of pellet injection technology. This specialized field of research originated as a possible solution to the problem of depositing atoms of fuel deep within magnetically confined, hot plasmas for refueling of fusion power reactors. Using pellet injection systems, frozen macroscopic (millimeter-size) pellets composed of the isotopes of hydrogen are formed, accelerated, and transported to the plasma for fueling. The process and benefits of plasma fueling by this approach have been demonstrated conclusively on a number of toroidal magnetic confinement configurations; consequently, pellet injection is the leading technology for deep fueling of magnetically confined plasmas for controlled thermonuclear fusion research. Hydrogen pellet injection devices operate at very low temperatures ((approximately-equal-to)10 K) at which solid hydrogen ice can be formed and sustained. Most injectors use conventional pneumatic (light gas gun) or centrifuge (mechanical) acceleration concepts to inject hydrogen or deuterium pellets at speeds of (approximately-equal-to)1–2 km/s. Pellet injectors that can operate at quasi-steady state (pellet delivery rates of 1–40 Hz) have been developed for long-pulse fueling. The design and operation of injectors with the heaviest hydrogen isotope, tritium, offer some special problems because of tritium's radioactivity. To address these problems, a proof-of-principle experiment was carried out in which tritium pellets were formed and accelerated to speeds of 1.4 km/s. Tritium pellet injection is scheduled on major fusion research devices within the next few years. Several advanced accelerator concepts are under development to increase the pellet velocity. One of these is the two-stage light gas gun, for which speeds of slightly over 4 km/s have already been reported in laboratory experiments with deuterium ice. A few two-stage pneumatic systems (single-shot) have recently been installed on tokamak experiments. This article reviews the equipment and instruments that have been developed for pellet injection with emphasis on recent advances. Prospects for future development are addressed, as are possible applications of this technology to other areas of research.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143995
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Performance of a pneumatic hydrogen-pellet injection system on the Joint European Torus (1989)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 60 (1989), S. 2697-2700 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A pneumatic-based, hydrogen isotope pellet injector that was developed at the Oak Ridge National Laboratory (ORNL) has been used in recent plasma fueling experiments on the Joint European Torus (JET). The injector consists of three independent machine-gun-like mechanisms (nominal pellet sizes of 2.7, 4.0, and 6.0 mm in diameter) and features repetitive operation (1–5 Hz) for quasi-steady-state conditions (〉10 s). An extensive set of injector diagnostics permits evaluation of parameters for each pellet shot, including speed, mass, and integrity. Pellet speeds range from 1.0 to 1.5 km/s. Over 3700 pellets have been fired with the equipment at JET, with about 1500 pellets shot for plasma fueling experiments. In recent experiments, the system performance has been outstanding, including excellent reproducibility in pellet speed and mass, and a reliability of 〉98% in delivery of pellets to the plasma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140643
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Fast-opening magnetic valve for high-pressure gas injection and applications to hydrogen pellet fueling systems (1986)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 2356-2358 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A fast, magnetically driven gas valve and its application to pneumatic-based solid hydrogen pellet injectors are described. The valve, which is equipped with a polyimide stem tip (hard seal) and a 5-mm-diam orifice, can open against working pressures up to 140 bar (2000 psi). Other unique features of this design include temperature- and radiation-resistant seals, a programmable output pressure pulse, and repetitive operation in excess of 20 Hz. A prototype valve has been used to propel frozen hydrogen isotope pellets to speeds of up to 1900 m/s.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1138677
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...