385 Matching Results

Search Results

Advanced search parameters have been applied.

Hydromagnetic Stability of a Diffuse Linear Pinch

Description: Abstract: "The hydromagnetic energy principle is applied to the derivation of necessary and sufficient conditions for the hydromagnetic stability of a linear pinch with distributed plasma current (a diffuse linear pinch). The results are quite general in that the axial and azimuthal components of the magnetic field, which determines the structure of the pinch completely, are treated as arbitrary functions of distance from the axis. For purpose of illustration, the general results are applied to the limiting case of a pinch with the plasma current confined to an infinity thin layer (a sharp pinch)."
Date: August 1959
Creator: Newcomb, William A.
Partner: UNT Libraries Government Documents Department

Boundary-layer formation in the pinch

Description: From abstract: "A study is made of various processes that occur prior to the pinch effect when an electric field is applied to a deuterium gas. The variables of the problem are percentage of ionization, the electron and ion temperatures, the resistivity of the gas, and the current density."
Date: August 10, 1959
Creator: Killeen, John; Gibson, Gordon & Colgate, Stirling A.
Partner: UNT Libraries Government Documents Department

Turbulent Pinch Experiments

Description: This report follows studies that were made the quasi-stable pinch produced by a relatively long duration low voltage capacitor discharge (5ma, 5kv) in a 600 cm long, 15 cm diameter metal tube.
Date: 1957
Creator: Sawyer, G. A. & Stratton, T. F.
Partner: UNT Libraries Government Documents Department

Neutron Production in the Pinch Due to Instability Breakup

Description: Abstract: "The neutrons from the linear pinch in Berkeley have been shown to originate from deuteron collisions with a large net center-of-mass velocity in one direction along the axis of the pinch tube. The interpretation of this result is that the neutron production associated with the pinch is non-thermonuclear in origin. The object of this paper is to review the experimental evidence and discuss a possible source of the neutron production."
Date: May 12, 1956
Creator: Colgate, Stirling A.
Location Info:
Partner: UNT Libraries Government Documents Department

The Hard-Core Pinch. II

Description: This report describes a toroidal version of the hard-core pinch and the additional information it can obtain to what the analogous linear pinch can get.
Date: July 31, 1959
Creator: Birdsall, D. H.; Colgate, Stirling A. & Furth, Harold P.
Partner: UNT Libraries Government Documents Department

The Hard-Core Pinch. I

Description: This report analyzes a linear, hard-core pinch tube built to examine tubes afflicted by small-scale instabilities evident from many observations.
Date: July 31, 1959
Creator: Birdsall, D. H.; Colgate, Stirling A. & Furth, Harold P.
Partner: UNT Libraries Government Documents Department

Large Toroidal Stabilized Pinch Proposal

Description: This report focuses on the study of the stabilized pinch program made to increase the plasma temperature and improve the plasma conductivity and containment. One method proposed is the usage of a large toroidal stabilized pinch, which is described here.
Date: January 29, 1958
Creator: Colgate, Stirling A. & Furth, H. P.
Partner: UNT Libraries Government Documents Department

Pressure Balance in a Toroidal Pinch

Description: Abstract: In the study of a linear pinch, use of the equation of pressure balance has proven to be a powerful method of analyzing data taken with a magnetic probe. The toroidal pinch, however, is a geometrically more complicated object, and the use of the pressure balance equations is not so clean cut. It is the object of this note to analyze the pressure balance equations for a torus to the point where they might prove useful in interpreting probe data.
Date: December 1958
Creator: Suydam, Bergen R.
Partner: UNT Libraries Government Documents Department

Small-Scale Instabilites of the Pinch and a Suggested Remedy: The Levitron

Description: Report discussing "experimental results on the classical stabilized pinch," "the usefulness of the Levitron in Stellarator-type operation," and "practical details of the levitation process." A configuration is presented which involves a "toroidal pinch tube inside which a rigid toroidal conductor is levitated by means of an induced magnetic field." Additionally, "an alternative scheme is considered, where the toroidal core is suspended from current-carrying wires, but this approach does not appear promising."
Date: September 1958
Creator: Colgate, Stirling A. & Furth, H. P.
Partner: UNT Libraries Government Documents Department

Proposal for a High-Current Discharge Tube With Capacitor

Description: Abstract: This proposal describes a parallel-plate capacitor and the discharge tube with which it is hoped that implosion energies of 1000 eV can be given to deuterons by the pinch effect. The discharge tube is to be arranged so that no external series switch is required.
Date: March 18, 1955
Creator: Bostick, Winston H.
Partner: UNT Libraries Government Documents Department

Application of 2-D Simulations to Z-Pinch Experiment Design and Analysis

Description: The successful 2-D simulations of z-pinch experiments (reproducing such features as the measured experimental current drive, radiation pulse shape, peak power and total radiated energy) can lead to a better understanding of the underlying physics in z-pinch implosions and to the opportunity to use such simulations in the analysis of experimental data and in the design of new experiments. Such use has been made with LANL simulations of experiments on the Sandia Saturn and Z accelerators. Applications have included ''vacuum'' and ''dynamic'' hohlraum experiments; variations in mass, radius and length; and ''nested'' array configurations. Notable examples include the explanation of the power/length results in reduced length pinches and the prediction of the current best power and pulsewidth nested array experiment. Examples of circumstances where the simulation results do not match the experiments will be given along with a discussion of opportunities for improved simulation results.
Date: October 19, 1998
Creator: Peterson, D.L.; Bowers, R.L.; Matuska, W.; Chandler, G.A.; Deeney, C.; Derzon, M.S. et al.
Partner: UNT Libraries Government Documents Department

The Physics of Long-Pulse Wire Array Z-Pinch Implosions

Description: Recent improvements in z-pinch wire array load design at Sandia National Laboratories have led to a substantial increase in pinch performance as measured by radiated powers of up to 280 TW in 4 ns and 1.8 MJ of total radiated energy. Next generation, higher current machines will allow for larger mass arrays and comparable or higher velocity implosions to be reached, possibly extending these result.dis the current is pushed above 20 MA, conventional machine design based on a 100 ns implosion time results in higher voltages, hence higher cost and power flow risk. Another approach, which shifts the risk to the load configuration, is to increase the implosion time to minimize the voltage. This approach is being investigated in a series of experimental campaigns on the Saturn and Z machines. In this paper, both experimental and two dimensional computational modeling of the fist long implosion Z experiments will be presented. The experimental data shows broader pulses, lower powers, and larger pinch diameters compared to the corresponding short pulse data. By employing a nested array configuration, the pinch diameter was reduced by 50% with a corresponding increase in power of > 30%. Numerical simulations suggest load velocity is the dominating mechanism behind these results.
Date: December 14, 1999
Creator: DOUGLAS,MELISSA R.; DEENEY,CHRISTOPHER; SPIELMAN,RICK B.; COVERDALE,CHRISTINE A.; RODERICK,N.F. & PETERSON,D.L.
Partner: UNT Libraries Government Documents Department

Laser Diagnostics for Wire Array Z-Pinch Shock Physics Experiments

Description: The Z Accelerator is a fast pulse power facility capable of performing high-pressure studies of the dynamic response of materials under loading conditions unachievable with other methods. A variety of advanced laser diagnostics have been implemented on the facility for shock physics experiments. These include multipoint laser velocity interferometry,line and full field velocity interferometry, time-resolved optical and uv spectroscopy, and both active and passive shock breakout.
Date: September 1, 1999
Creator: Asay, James R.; Bailey, James E.; Hall, Clint A.; Knudson, Marcus D. & Trott, Wayne M.
Partner: UNT Libraries Government Documents Department

Initial Conditions for the Dynamic Pinch

Description: Abstract: "The experimental formation of the dynamic pinch has been an art based upon available electrical condensers, available glass and quartz tubing and an empirically determined gas pressure range. This report attempts to correlate some of this empirical information with the processes of ionization, insulator wall heating, magnetic field penetration, and shock hydrodynamics."
Date: March 1957
Creator: Colgate, Stirling A.
Partner: UNT Libraries Government Documents Department

Exploring Ways to Improve Predictive Capability of Z-Pinch Calculations

Description: For some time 2-dimensional RMHD (radiation magneto-hydrodynamic) calculations of radiating z-pinches have been made to agree with integral data (current wave form, yield and power). For these calculations, the agreement with detailed data, such as time-resolved x-ray images, is generally not as good. Correctly modeling the physics of z-pinches, including detailed data, is needed to have true predictive capability. To address this problem, the authors first determine which integral data are most sensitive to the details in the models. With this information, they investigate aspects of the pinch, to which the data is sensitive, using non-standard techniques. For example, the pinch is calculated in (x,y)-geometry to investigate how a non-symmetric implosion affects the simulated data.
Date: October 19, 1998
Creator: Matuska, W.; Aubrey, J.; Bowers, R.; Lee, H.; Peterson, D.; Deeney, C. et al.
Partner: UNT Libraries Government Documents Department

X-ray emission from a high-atomic-number z-pinch plasma created from compact wire arrays

Description: Thermal and nonthermal x-ray emission from the implosion of compact tungsten wire arrays, driven by 5 MA from the Saturn accelerator, are measured and compared with LLNL Radiation-Hydro-Code (RHC) and SNL Hydro-Code (HC) numerical models. Multiple implosions, due to sequential compressions and expansions of the plasma, are inferred from the measured multiple x-radiation bursts. Timing of the multiple implosions and the thermal x-ray spectra measured between 1 and 10 keV are consistent with the RHC simulations. The magnitude of the nonthermal x-ray emission measured from 10 to 100 keV ranges from 0.02 to 0.08% of the total energy radiated and is correlated with bright-spot emission along the z-axis, as observed in earlier Gamble-11 single exploding-wire experiments. The similarities of the measured nonthermal spectrum and bright-spot emission with those measured at 0.8 MA on Gamble-II suggest a common production mechanism for this process. A model of electron acceleration across magnetic fields in highly-collisional, high-atomic-number plasmas is developed, which shows the existence of a critical electric field, E{sub c}, below which strong nonthermal electron creation (and the associated nonthermal x rays) do not occur. HC simulations show that significant nonthermal electrons are not expected in this experiment (as observed) because the calculated electric fields are at least one to two orders-of-magnitude below E{sub c}. These negative nonthermal results are confirmed by RHC simulations using a nonthermal model based on a Fokker-Plank analysis. Lastly, the lower production efficiency and the larger, more irregular pinch spots formed in this experiment relative to those measured on Gamble II suggest that implosion geometries are not as efficient as single exploding-wire geometries for warm x-ray production.
Date: March 1, 1996
Creator: Sanford, T.W.L.; Nash, T.J. & Marder, B.M.
Partner: UNT Libraries Government Documents Department

Potential enhancement of warm x-ray dose from a reflexing bremsstrahlung diode

Description: The potential for generating intense bursts of war x rays (20 to 60 keV) using electron reflexing diodes on pulsed-power accelerators is evaluated with the TIGER Monte Carlo code, showing that hundreds of kilojoules of warm x rays can be generated under idealized conditions. The calculation are compared with data from Gamble-II experiments and applied to two suggest Jupiter (60-MA, 5-MV, 100-ns) diode configurations. If the simultaneous irradiation from the high-energy tail of the bremsstrahlung which accompanies the warm x rays is a concern, then the reflexing technique is shown to be limited to the irradiation of targets thinner than {approximately} 400 {mu}m for low-Z targets like aluminum and thinner than {approximately} 5 {mu}m for high-Z targets like gold.
Date: July 1, 1995
Creator: Sanford, T.W.L.; Halbleib, J.A.; Cooperstein, G. & Weber, B.V.
Partner: UNT Libraries Government Documents Department