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Wavelength scaling of laser plasma coupling (open access)

Wavelength scaling of laser plasma coupling

The use of shorter wavelength laser light both enhances collisional absorption and reduces deleterious collective plasma effects. Coupling processes which can be important in reactor-size targets are briefly reviewed. Simple estimates are presented for the intensity-wavelength regime in which collisional absorption is high and collective effects are minimized.
Date: November 3, 1983
Creator: Kruer, W.L.
System: The UNT Digital Library
Normal zone detectors for a large number of inductively coupled coils. Revision 1 (open access)

Normal zone detectors for a large number of inductively coupled coils. Revision 1

In order to protect a set of inductively coupled superconducting magnets, it is necessary to locate and measure normal zone voltages that are small compared with the mutual and self-induced voltages. The method described in this paper uses two sets of voltage measurements to locate and measure one or more normal zones in any number of coupled coils. One set of voltages is the outputs of bridges that balance out the self-induced voltages. The other set of voltages can be the voltages across the coils, although alternatives are possible. The two sets of equations form a single combined set of equations. Each normal zone location or combination of normal zones has a set of these combined equations associated with it. It is demonstrated that the normal zone can be located and the correct set chosen, allowing determination of the size of the normal zone. Only a few operations take place in a working detector: multiplication of a constant, addition, and simple decision-making. In many cases the detector for each coil, although weakly linked to the other detectors, can be considered to be independent. The effect on accuracy of changes in the system parameters is discussed.
Date: November 3, 1983
Creator: Owen, E. W. & Shimer, D. W.
System: The UNT Digital Library
Status of the glueballs (open access)

Status of the glueballs

If you assume as input axioms: (1) QCD is correct; and (2) the OZI rule is universal for weakly coupled glue in disconnected Zweig diagrams where the disconnection is due to the creation or annihilation of new flavor(s) of quark(s), then the BNL/CCNY g/sub T/(2010), g/sub T/'(2220) and g/sub T/(2360) observed in ..pi../sup -/p ..-->.. phi phi n are produced by 1-3 primary glueballs. One or two broad primary glueballs could in principle break down the OZI suppression and mix with one or two quark states which accidentally have the same quantum numbers and nearly the same mass. However the simplest explanation of the rather unusual characteristics of our data is that we have found a triplet of J/sup PC/ = 2/sup + +/ glueball states. Since our input axioms are in good agreement with experiments and merely represent modern QCD practice, we have very probably discovered 1-3 J/sup PC/ = 2/sup + +/ glueballs. The iota(1440) and the theta(1700) observed in J/psi radiative decay are glueball candidates. The pros and cons of which are discussed briefly here. 41 references.
Date: August 3, 1983
Creator: Lindenbaum, S. J.
System: The UNT Digital Library
LLNL TMX-U diagnostics data system (open access)

LLNL TMX-U diagnostics data system

The TMX-U data system is a general-purpose system for acquiring, analyzing, and output of TMX-U data, and can also apply to any pulsed controlled thermonuclear experiment. In its present implementation, it routinely acquires 3 Mbytes of data per shot at an average rate of one shot every 8 minutes. For increased throughput, the system uses 5 CPUs accessing shared disk memory with a capacity of about 500 Mbytes. All acquisition, analysis, and output of data is handled by a collection of standard program modules (processors), which can be linked together to form chained calculations. Processing for various shots may be allowed to overlap, with higher priority results being available quickly, while lower priority results being allowed to lag behind and catch up in natural lulls in the experiment. Selection of tasks (processor invokations) is done independently by each of the 5 CPUs in the system, and each task can run in any suitable CPU.
Date: June 3, 1983
Creator: Parrish, C.P. & Clauser, J.F.
System: The UNT Digital Library
Subnanosecond-rise-time, low-impedance pulse generator (open access)

Subnanosecond-rise-time, low-impedance pulse generator

This paper describes a fast rise, low-impedance pulse generator that has been developed at the Lawrence Livermore National Laboratory. The design specifications of this generator are: 50-kV operating voltage, 1-ohm output impedance, subnanosecond rise time, and a 2 to 10 nanosecond pulse length. High repetition rate is not required. The design chosen is a parallel-plate, folded Blumlein generator. A tack switch is utilized for its simple construction and high performance. The primary diagnostic is a capacitive voltage divider with a B probe used to measure the current waveform.
Date: June 3, 1983
Creator: Druce, R. & Vogtlin, G.
System: The UNT Digital Library
Confirmation of the calculated breeding ratio for CRBRP (open access)

Confirmation of the calculated breeding ratio for CRBRP

A breeding ratio of at least 1.2 was a design goal for CRBRP. The value for the initial core (using plutonium with 11% /sup 240/Pu) calculated with ENDF/B-IV data is 1.27. Engineering mock-up studies for CRBRP were made in ZPPR-11. Analysis of ZPPR-11 using ENDF/B-IV data showed consistent underprediction of K/sub eff/ by about 1.5% and overpredictions of the /sup 238/U capture to /sup 239/Pu fission ratio (C8/F9) between 5% and 8%. These results are typical for all LMFBR critical assemblies at ANL. The following approach was used to determine the breeding ratio: sensitivity analysis of a range of fast reactor benchmarks and a fit to the experimental data by data adjustment; tests of the adjusted data against experiments in ZPPR-11; calculations for CRBRP with ENDF/B-IV data and the adjusted data to predict the breeding ratio bias; and estimates of k/sub eff/ and breeding ratio uncertainties using data sensitivities for CRBRP.
Date: June 3, 1983
Creator: Collins, P.J.; Liaw, J. & Turski, R.
System: The UNT Digital Library
Thermal performance of the MFTF magnets (open access)

Thermal performance of the MFTF magnets

A yin-yang pair of liquid-helium (LHe) cooled, superconducting magnets were tested last year at the Lawrence Livermore National Laboratory (LLNL) as part of a series of tests with the Mirror Fusion Test Facility (MFTF). These tests were performed to determine the success of engineering design used in major systems of the MFTF and to provide a technical base for rescoping from a single-mirror facility to the large tandem-mirror configuration (MFTF-B) now under construction. The magnets were cooled, operated at their design current and magnetic field, and warmed to atmospheric temperature. In this report, we describe their thermal behavior during these tests.
Date: August 3, 1983
Creator: VanSant, J.H.
System: The UNT Digital Library
Spectrochemical analysis of plutonium using direct current plasma emission spectrometry (open access)

Spectrochemical analysis of plutonium using direct current plasma emission spectrometry

One year ago, LLNL was just completing the installation of a Direct Current Plasma (DCP) spectrometer for the analysis of Pu and Pu alloys. The installation was completed in December 1982 and has been utilized regularly for Pu analysis since then. This paper discusses the experience with the instrument and some data demonstrating its performance.
Date: December 3, 1983
Creator: Morris, W.F.; Fadeff, S.K. & Torres, S.
System: The UNT Digital Library
Thresholds of Raman backscatter: effects of collisions and Landau damping (open access)

Thresholds of Raman backscatter: effects of collisions and Landau damping

We present 1.5 dimensional simulations and theory of the threshold of Raman backscatter for a variety of density profiles, background temperatures and collision frequencies, nu/sub ei/. The simulations show Raman backscatter of approx. 4 x 10/sup -4/ at intensities approx. 30 times below the del n threshold which we suggest is due to light scattering off of noise electron plasma waves. The absorption drops significantly and the threshold rises as the Landau damping ..omega../sub i/ and/or nu/sub ei/ approach the growth rate ..gamma../sub 0/. Many experiments are already in the collisional regime.
Date: November 3, 1983
Creator: Estabrook, K. & Kruer, W.L.
System: The UNT Digital Library