3,195 Matching Results

Search Results

Advanced search parameters have been applied.

Notes on magnetic coil design

Description: This brief report summarizes work done which addressed the issue of sizing the USTX Ohmic heating solenoid by imposing some physical constraints on the TF and OH coil designs. A computer code is used for this study. The TF coil sets the solenoid inner radius at 0.10 meters. Allowing a 2.5 cm gap between the inner plasma radius and outer radius of the solenoid fixes the latter at 0.185 meters. The OH solenoid radial thickness is then 0.085 meters. The plasma current obtainable is I{sub p} = 1.05 megamp.
Date: May 11, 1995
Creator: Uglum, J.
Partner: UNT Libraries Government Documents Department

Improved fusion performance in low-q, low triangularity plasmas with negative central magnetic shear

Description: Fusion performance in DIII-D low-q single-null divertor discharges has doubled as a result of improved confinement and stability, achieved through modification of pressure and current density profiles. These discharges extend the regime of neoclassical core confinement associated with negative or weak central magnetic shear to plasmas with the low safety factor (q{sub 95}{approximately}3) and triangularity ({delta}{approximately}0.3) anticipated in future tokamaks such as ITER. Energy confinement times exceed the ITER-89P L- mode scaling law by up to a factor of 4, and are almost twice as large as in previous single-null cases with 3{le}q{sub 95}{le}4. The normalized beta [{beta}(aB/I)] reaches values as high as 4, comparable to the best previous single-null discharges. Although high triangularity allows a larger plasma current, the fusion gain in these low triangularity plasmas is similar to that of high triangularity double-null plasmas at the same plasma current. These results are encouraging for advanced performance operation in ITER and for D-T experiments in JET.
Date: July 1, 1996
Creator: Strait, E.J.; Casper, T.N. & Chu, M.S.
Partner: UNT Libraries Government Documents Department

Interpretation of PISCES -- A RF antenna system experimental results

Description: The paper describes experimental data from rf coupling experiments using one to four coil antenna arrays that encircle a linear magnetized plasma column. Experimental results using single turn coil that produce symmetric (i.e. m = 0), dipole (m = 1), and radial rf magnetic fields for coupling to ion waves are compared. By operating without a Faraday shield, it was observed for the first time that the plasma resistive load seen by these different antenna types tends to increase with the number of turns to at least the second power. A four-turn m = 0 coil experienced a record 3--5 {Omega} loading, corresponding to over 90% power coupling to the plasma. A four-turn m = 1 coil experienced up to 1--1.5 {Omega} loading, also higher than previous observations. First time observations using a two coil array of m = 0 coil are also reported. As predicted, the loading decreases with increasing phase between coil from 0{degree} to 180{degree}. Experiments using four coil arrays were difficult to optimize and interpret primarily due to complexity of the manual tuning. To facilitate this optimization in the future, a proposed feedback control system that automatically matches load variations between 0.2 and 10 {Omega} is described.
Date: October 1995
Creator: Rothweil, D. A.; Phelps, D. A. & Doerner, R.
Partner: UNT Libraries Government Documents Department

Comparison of methods for separating small quantities of hydrogen isotopes from an inert gas

Description: It is frequent within tritium processing systems that a small amount of hydrogen isotopes (Q{sub 2}) must be separated from an inert gas such as He, Ar and N{sub 2}. Thus, a study of presently available technologies for effecting such a separation was performed. A base case and seven technology alternatives were identified and a simple design of each was prepared. These technologies included oxidation-adsorption-metal bed reduction, oxidation-adsorption-palladium membrane reactor, cryogenic adsorption, cryogenic trapping, cryogenic distillation, hollow fiber membranes, gettering and permeators. It was found that all but the last two methods were unattractive for recovering Q{sub 2} from N{sub 2}. Reasons for technology rejection included (1) the method unnecessarily turns the hydrogen isotopes into water, resulting in a cumbersome and more hazardous operation, (2) the method would not work without further processing, and (3) while the method would work, it would only do so in an impractical way. On the other hand, getters and permeators were found to be attractive methods for this application. Both of these methods would perform the separation in a straightforward, essentially zero-waste, single step operation. The only drawback for permeators was that limited low-partial Q{sub 2} pressure data is available. The drawbacks for getters are their susceptibility to irreversible and exothermic reaction with common species such as oxygen and water, and the lack of long-term operation of such beds. More research is envisioned for both of these methods to mature these attractive technologies.
Date: March 1, 1998
Creator: Willms, R.S.; Tuggle, D.; Birdsell, S.; Parkinson, J.; Price, B. & Lohmeir, D.
Partner: UNT Libraries Government Documents Department

Magnetic Probe Construction using Thick-film Technology

Description: Thick-film technology has been successfully adapted for the design and fabrication of magnetic probes of a new type suitable for use in the simultaneous ultra-high vacuum and high-temperature environment of a nuclear fusion device. The maximum usable temperature is expected to be around 900 degrees C. This new probe has a specific sensitivity (coupling area per unit volume) an order of magnitude higher than a conventional coil. The new probe in one implementation is capable of simultaneously measuring magnetic field in three orthogonal directions about a single spatial point and in two frequency ranges. Low-frequency coils have a measured coupling area of 296-323 cm squared and a frequency response of about 300 kHz. High-frequency coils have a design coupling area of 12-15 cm squared.
Date: February 2, 2001
Creator: Takahashi, H.; Sakakibara, S.; Kubota, Y. & and Yamada, H.
Partner: UNT Libraries Government Documents Department

Maintaining the closed magnetic-field-line topology of a field-reversed configuration (FRC) with the addition of static transverse magnetic fields

Description: The effects on magnetic-field-line structure of adding various static transverse magnetic fields to a Solovev-equilibrium field-reversed configuration is examined. It is shown that adding fields that are anti-symmetric about the axial mid-plane maintains the closed field-line structure, while adding fields with planar or helical symmetry opens the field structure. Anti-symmetric modes also introduce pronounced shear.
Date: January 13, 2000
Creator: Cohen, S.A. & Milroy, R.D.
Partner: UNT Libraries Government Documents Department

Liquid first walls for magnetic fusion energy

Description: Liquids ({approximately}7 neutron mean free paths thick) with certain restrictions can probably be used in magnetic fusion designs between the burning plasma and the structural materials of the plant. If this works there are a number of profound advantages: lower the cost of electricity by more than 35%; remove the need to develop first wall materials saving over 4B$ in development costs; reduce the amount and kind of wastes generated in the plant; and permit a wider choice of materials. Evaporated liquid must be efficiently ionized in an edge plasma to prevent penetrating into the burning plasma and diminishing the burn rate. The fraction of evaporated material ionized is estimated to be 0.993 for Li, 0.98 for Flibe and 0.9999 for Li{sub 17}Pb{sub 83}. This ionized vapor would be swept along open field lines into a remote burial chamber. The most practical systems would be those with topological open field lines on the outer surface as is the case of a field reversed configuration (FRC), a Spheromak, a Z-pinch, or a mirror machine. In a Tokamak, including the Spherical Tokamak, the field lines outside the separatrix are restricted to a small volume inside the toroidal coil making for difficulties in introducing the liquid and removing the ionized vapor.
Date: March 28, 1996
Creator: Moir, R.W.
Partner: UNT Libraries Government Documents Department

Description of a Thermonuclear Reactor Based on the Use of a Layer of Relativistic Electrons to Confine and Heat the Plasma

Description: A long layer of rotating relativistic electrons was employed in a proposed scheme of a thermonuclear reactor to provide a closed pattern of magnetic field liens and to heat the plasma to fusion temperature. Parameters of a production machine and experimental model are presented. The general requirements for the plasma confinement at adequate density and temperature are summarized. Establishment of the electron layer is described. The equilibrium of the plasma under these conditions was investigated and the stability of this equilibrium distribution determined. (M.C.G.)
Date: March 14, 1957
Creator: Christofilos, N. C.
Partner: UNT Libraries Government Documents Department

Fusion Ignition Research Experiment System Integration

Description: The FIRE (Fusion Ignition Research Experiment) configuration has been designed to meet the physics objectives and subsystem requirements in an arrangement that allows remote maintenance of in-vessel components and hands-on maintenance of components outside the TF (toroidal-field) boundary. The general arrangement consists of sixteen wedged-shaped TF coils that surround a free-standing central solenoid (CS), a double-wall vacuum vessel and internal plasma-facing components. A center tie rod is used to help support the vertical magnetic loads and a compression ring is used to maintain wedge pressure in the inboard corners of the TF coils. The magnets are liquid nitrogen cooled and the entire device is surrounded by a thermal enclosure. The double-wall vacuum vessel integrates cooling and shielding in a shape that maximizes shielding of ex-vessel components. The FIRE configuration development and integration process has evolved from an early stage of concept selection to a higher level of machine definition and component details. This paper describes the status of the configuration development and the integration of the major subsystem components.
Date: November 1, 1999
Creator: Brown, T.
Partner: UNT Libraries Government Documents Department


Description: The major effort of the Livermore Mirror Machine group is directed toward study of plasma stabllity and confinement in mirror geometries. The status and radial density distribution and diffusion of confined plasma are briefly summarized. The ALICE Experiment (Adiabatic Lowenergy Injection and Capture Experiment) is discussed in some detnil. (W.D.M.)
Date: January 20, 1960
Creator: Post, R.F.
Partner: UNT Libraries Government Documents Department


Description: Components of the program not specifically covered in the preceding report are brought up to date. Elements of the program in which no significant results were produced are mentioned only briefly. Activities are reported under the following headings: Pyrotron Program; High-energy Injection; Astron Program: Livermore Pinch Program; Berkeley Pinch Program; Ion Magnetron: Theoretical Research: Basic Experimental Research; and Engineering and Technological Development. (For preceding period see UCRL-8682.) (W.D.M.)
Date: November 1, 1959
Creator: Seidman, T
Partner: UNT Libraries Government Documents Department

A Fusion Chamber for the 2002 Robust Point Design

Description: A top-level overview of the mechanical design for the 2002 Robust Point Design (RPD-2002) fusion chamber is introduced. It is based on the HYLIFE-II design and includes modifications to the liquid pocket configuration and first structural wall (FSW), facilitates periodic maintenance or replacement of internal components, and is compliant with all other RPD-2002 parameters. This work has been carried out by constructing a parametric computer model capable of being updated as future changes become necessary.
Date: October 1, 2003
Creator: Abbott, R P
Partner: UNT Libraries Government Documents Department

Radiocarbon in otoliths of yelloweye rockfish (Sebastes ruberrimus): a reference time series for the coastal waters of southeast Alaska

Description: Atmospheric testing of thermonuclear devices during the 1950s and 1960s created a global radiocarbon ({sup 14}C) signal in the environment that has provided a useful tracer and chronological marker in oceanic systems and organisms. The bomb-generated {sup 14}C signal retained in fish otoliths can be used as a permanent, time-specific recorder of the 14C present in ambient seawater, making it a useful tool in age validation of fishes. The goal of this study was to determine {sup 14}C levels in otoliths of the age-validated yelloweye rockfish (Sebastes ruberrimus) to establish a reference time series for the coastal waters of southeast Alaska. Radiocarbon values from the first year's growth of 43 yelloweye rockfish otoliths were plotted against estimated birth year to produce a 14C time series for these waters spanning 1940 to 1990. The time series shows the initial rise of bomb 14C occurred in 1958 in coastal southeast Alaskan waters and {sup 14}C levels rose relatively rapidly to peak {Delta}{sup 14}C values (60-70%) between 1966 and 1971, with a subsequent declining trend through the end of the record in 1990 (-3.2%). In addition, the radiocarbon data, independent of the radiometric study, confirms the longevity of the yelloweye rockfish up to a minimum of 44 years and strongly supports higher age estimates. The yelloweye rockfish record provides a {sup 14}C chronology that will be useful for the interpretation of {sup 14}C accreted in biological samples from these waters and in future rockfish age validation studies.
Date: October 14, 2003
Creator: Kerr-Ferrey, L A; Andrews, A H; Frantz, B R; Coale, K H; Brown, T A & Cailliet, G M
Partner: UNT Libraries Government Documents Department

Evaluation of wave dispersion, mode-conversion, and damping for ECRH with exact relativistic corrections

Description: The complex dispersion functions of Eq. (3) in Ref. 1 have recently been computed accurately and reliably over their entire range of parameters, without recourse to the usual slightly-relativistic approximation, which may have difficulty for oblique incidence. In the future, the local dispersion properties of ECRF waves will be reevaluated for parameters of interest to ECRF conditions in several existing and proposed fusion experiments, with particular emphasis on the damping and mode-conversion of both ordinary and extraordinary waves to electrostatic waves near the upper hybrid and cyclotron frequencies.
Date: December 31, 1991
Creator: Smithe, D.N. & Colestock, P.L.
Partner: UNT Libraries Government Documents Department

MHD modelling of liquid metal films for fusion divertor surface protection

Description: In order to counter adverse effects resulting from the impingement of high energy plasmas on solid material surfaces, especially as this relates to fusion reactor high heat flux components, the idea of protecting the material surface with a thin film of liquid metal has been advanced. In principle, this film would protect the underlying substrate from physical sputtering and reduce thermal stresses in the structure. However, serious concerns related to establishing such a liquid metal flow and its performance in a fusion environment need to be addressed. In particular, the interaction of the conducting metal film with the complicated magnetic fields typical of a diverted reactor plasma may lead to retardation of the film resulting in channel flooding, velocity profiles not conducive to effective heat transfer, and possibly even detachment of the film from the substrate. In addition, the momentum carried by the plasma particles may deform the film shape to a significant extent, possibly disrupting the flow or leaving sections on the substrate inadequately protected. Proposed here are several mathematical and experimental models intended to address these specific questions. Mathematical models will be derived from the basic set of incompressible magnetohydrodynamic equations for the cases of fully developed and developing film flow. The fully developed flow model allows simplification of the governing equations to two dimensions, facilitating their solution. The data obtained from this formulation will yield the velocity, induced magnetic field, and height of the film as a function of space and flow parameters. From this data the effect of the plasma momentum on the shape of the surface will be seen, as will the velocity structure across the channel, a structure that is only assumed in previous modeling attempts. The developing film model, based on simplifying assumptions for the height and velocity profiles determined from the previous ...
Date: December 31, 1991
Creator: Morley, N. B.
Partner: UNT Libraries Government Documents Department