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Intramolecular condensation reactions of {alpha}, {omega}- bis(triethoxy-silyl)alkanes. Formation of cyclic disilsesquioxanes (open access)

Intramolecular condensation reactions of {alpha}, {omega}- bis(triethoxy-silyl)alkanes. Formation of cyclic disilsesquioxanes

Under acidic sol-gel polymerization conditions, 1,3-bis(triethoxysilyl)-propane (1) and 1,4-bis(triethoxysilyl)butane (2) were shown to preferentially form cyclic disilsesquioxanes 3 and 4 rather than the expected 1,3-propylene- and 1,4-butylene-bridged polysilsesquioxane gels. Formation of 3 and 4 is driven by a combination of an intramolecular cyclization to six and seven membered rings, and a pronounced reduction in reactivity under acidic conditions as a function of increasing degree of condensation. The ease with which these relatively unreactive cyclic monomers and dimers are formed (under acidic conditions) helps to explain the difficulties in forming gels from 1 and 2. The stability of cyclic disilsesquioxanes was confirmed withe the synthesis of 3 and 4 in gram quantities; the cyclic disilsesquioxanes react slowly to give tricyclic dimers containing a thermodynamically stable eight membered siloxane ring. Continued reactions were shown to perserve the cyclic structure, opening up the possibility of utilizing cyclic disilsesquioxanes as sol-gel monomers. Preliminary polymerization studies with these new, carbohydrate-like monomers revealed the formation of network poly(cyclic disilsesquioxanes) under acidic conditions and polymerization with ring-opening under basic conditions.
Date: August 1, 1996
Creator: Loy, Douglas A.; Carpenter, Joseph P.; Myers, Sharon A.; Assink, Roger A.; Small, James H.; Greaves, John et al.
Object Type: Article
System: The UNT Digital Library
Measurement of the alpha asymmetry parameter for the Omega- ---> Lambda K- decay (open access)

Measurement of the alpha asymmetry parameter for the Omega- ---> Lambda K- decay

None
Date: February 1, 2005
Creator: Chen, Y. C.; /Taiwan, Inst. Phys.; Burnstein, R. A.; Chakravorty, A.; Chan, A.; Choong, W. S. et al.
Object Type: Article
System: The UNT Digital Library
Omega phase formation in shock-loaded zirconium (open access)

Omega phase formation in shock-loaded zirconium

A shock recovery experiment and post-shock mechanical measurements were conducted on high-purity Zr. Mechanical properties of the Zr samples before and after the shock loading are compared and discussed in terms of the substructure evolution during the shock loading. Metastable {omega}-phase was found in the Zr sample following shock-loading to 7 GPa. A new orientation relationship between the {alpha} and {omega} phases was derived which does not agree with those previously reported in hydrostatic pressure experiments. A mechanism is proposed for the observed {alpha} {yields} {omega} transformation.
Date: August 1, 1993
Creator: Song, Shihong & Gray, G. T., III
Object Type: Report
System: The UNT Digital Library
Omega phase formation in titanium and titanium alloys (open access)

Omega phase formation in titanium and titanium alloys

Although the response of titanium alloys to dynamic loading is receiving increased attention in the literature (particularly in the area of shear-band formation), a more limited experimental database exists concerning the detailed structure/property relationships of titanium alloys subjected to shock loading. In this study, preliminary results concerning the influence of alloy chemistry on the property of omega-phase formation and its structure in three titanium alloys are presented. The influence of shock-wave deformation on the phase stability and substructure evolution of high-purity (low-interstitial) titanium, A-70 (3700 ppm oxygen) titanium, and Ti-6Al-4V were probed utilizing real-time velocity interferometry (VISAR) and soft'' shock-recovery techniques. VISAR wave profiles of shock-loaded high-purity titanium revealed the omega-phase pressure-induced transition to occur at approximately 10.4 GPa. Wave profile measurements on A-70 Ti shocked to pressures up to 35 GPa and Ti-6Al-4V shocked to pressures up to 25 GPa exhibited no evidence of a three-wave structure indicative of a pressure-induced phase transition. Neutron and X-ray diffractometry and TEM analysis confirmed the presence of retained {omega}-phase in the electrolytic-Ti and the absence of {omega}-phase in the shock-recovered A-70 Ti and Ti-6Al-4V. Suppression of the {alpha}-{omega} phase transition in A-70 Ti, containing a high interstitial oxygen content, is seen to …
Date: January 1, 1992
Creator: Gray, G. T., III; Morris, C. E. & Lawson, A. C.
Object Type: Article
System: The UNT Digital Library
Omega phase formation in titanium and titanium alloys (open access)

Omega phase formation in titanium and titanium alloys

Although the response of titanium alloys to dynamic loading is receiving increased attention in the literature (particularly in the area of shear-band formation), a more limited experimental database exists concerning the detailed structure/property relationships of titanium alloys subjected to shock loading. In this study, preliminary results concerning the influence of alloy chemistry on the property of omega-phase formation and its structure in three titanium alloys are presented. The influence of shock-wave deformation on the phase stability and substructure evolution of high-purity (low-interstitial) titanium, A-70 (3700 ppm oxygen) titanium, and Ti-6Al-4V were probed utilizing real-time velocity interferometry (VISAR) and ``soft`` shock-recovery techniques. VISAR wave profiles of shock-loaded high-purity titanium revealed the omega-phase pressure-induced transition to occur at approximately 10.4 GPa. Wave profile measurements on A-70 Ti shocked to pressures up to 35 GPa and Ti-6Al-4V shocked to pressures up to 25 GPa exhibited no evidence of a three-wave structure indicative of a pressure-induced phase transition. Neutron and X-ray diffractometry and TEM analysis confirmed the presence of retained {omega}-phase in the electrolytic-Ti and the absence of {omega}-phase in the shock-recovered A-70 Ti and Ti-6Al-4V. Suppression of the {alpha}-{omega} phase transition in A-70 Ti, containing a high interstitial oxygen content, is seen to …
Date: May 1, 1992
Creator: Gray, G. T., III; Morris, C. E. & Lawson, A. C.
Object Type: Article
System: The UNT Digital Library
Omega documentation (open access)

Omega documentation

OMEGA is a CRAY I computer program that controls nine codes used by LLNL Physical Data Group for: 1) updating the libraries of evaluated data maintained by the group (UPDATE); 2) calculating average values of energy deposited in secondary particles and residual nuclei (ENDEP); 3) checking the libraries for internal consistency, especially for energy conservation (GAMCHK); 4) producing listings, indexes and plots of the library data (UTILITY); 5) producing calculational constants such as group averaged cross sections and transfer matrices for diffusion and Sn transport codes (CLYDE); 6) producing and updating standard files of the calculational constants used by LLNL Sn and diffusion transport codes (NDFL); 7) producing calculational constants for Monte Carlo transport codes that use group-averaged cross sections and continuous energy for particles (CTART); 8) producing and updating standard files used by the LLNL Monte Carlo transport codes (TRTL); and 9) producing standard files used by the LANL pointwise Monte Carlo transport code MCNP (MCPOINT). The first four of these functions and codes deal with the libraries of evaluated data and the last five with various aspects of producing calculational constants for use by transport codes. In 1970 a series, called PD memos, of internal and informal memoranda …
Date: August 1, 1983
Creator: Howerton, R. J.; Dye, R. E.; Giles, P. C.; Kimlinger, J. R.; Perkins, S. T. & Plechaty, E. F.
Object Type: Report
System: The UNT Digital Library
Alfvenic behavior of alpha particle driven ion cyclotron emission in TFTR (open access)

Alfvenic behavior of alpha particle driven ion cyclotron emission in TFTR

Ion cyclotron emission (ICE) has been observed during D-T discharges in the Tokamak Fusion Test Reactor (TFTR), using rf probes located near the top and bottom of the vacuum vessel. Harmonics of the alpha cyclotron frequency ({Omega}{sub {alpha}}) evaluated at the outer midplane plasma edge are observed at the onset of the beam injection phase of TFTR supershots, and persist for approximately 100-250 ms. These results are in contrast with observations of ICE in JET, in which harmonics of {Omega}{sub {alpha}} evolve with the alpha population in the plasma edge. Such differences are believed to be due to the fact that newly-born fusion alpha particles are super-Alfvenic near the edge of JET plasmas, while they are sub-Alfvenic near the edge of TFTR supershot plasmas. In TFTR discharges with edge densities such that newly-born alpha particles are super-Alfvenic, alpha cyclotron harmonics are observed to persist. These results are in qualitative agreement with numerical calculations of growth rates due to the magnetoacoustic cyclotron instability.
Date: July 1, 1995
Creator: Cauffman, S.; Majeski, R. & McClements, K.G.
Object Type: Report
System: The UNT Digital Library
Observation of parity violation in the Omega- ---> Lambda K- decay (open access)

Observation of parity violation in the Omega- ---> Lambda K- decay

The {alpha} decay parameter in the process {Omega}{sup -} {yields} {Lambda}K{sup -} has been measured from a sample of 4.50 million unpolarized {Omega}{sup -} decays recorded by the HyperCP (E871) experiment at Fermilab and found to be [1.78 {+-} 0.19(stat) {+-} 0.16(syst)] x 10{sup -2}. This is the first unambiguous evidence for a nonzero {alpha} decay parameter, and hence parity violation, in the {Omega}{sup -} {Lambda}K{sup -} decay.
Date: May 1, 2005
Creator: Lu, L. C.; U., /Virginia; Burnstein, R. A.; Chakravorty, A.; Chen, Y. C.; Choong, W.-S. et al.
Object Type: Article
System: The UNT Digital Library
Alpha Particle Destabilization of the Toroidicity-Induced Alfven Eigenmodes (open access)

Alpha Particle Destabilization of the Toroidicity-Induced Alfven Eigenmodes

The high frequency, low mode number toroidicity-induced Alfven eigenmodes (TAE) are shown to be driven unstable by the circulating and/or trapped {alpha}-particles through the wave-particle resonances. Satisfying the resonance condition requires that the {alpha}-particle birth speed v{sub {alpha}} {ge} v{sub A}/2{vert bar}m-nq{vert bar}, where v{sub A} is the Alfven speed, m is the poloidal model number, and n is the toroidal mode number. To destabilize the TAE modes, the inverse Landau damping associated with the {alpha}-particle pressure gradient free energy must overcome the velocity space Landau damping due to both the {alpha}-particles and the core electrons and ions. The growth rate was studied analytically with a perturbative formula derived from the quadratic dispersion relation, and numerically with the aid of the NOVA-K code. Stability criteria in terms of the {alpha}-particle beta {beta}{sub {alpha}}, {alpha}-particle pressure gradient parameter ({omega}{sub {asterisk}}/{omega}{sub A}) ({omega}{sub {asterisk}} is the {alpha}-particle diamagnetic drift frequency), and (v{sub {alpha}}/v{sub A}) parameters will be presented for TFTR, CIT, and ITER tokamaks. The volume averaged {alpha}-particle beta threshold for TAE instability also depends sensitively on the core electron and ion temperature. Typically the volume averaged {alpha}-particle beta threshold is in the order of 10{sup {minus}4}. Typical growth rates of the …
Date: October 1, 1990
Creator: Cheng, C. Z.
Object Type: Report
System: The UNT Digital Library
Charged Particle Spectroscopy on Omega (Final report) (open access)

Charged Particle Spectroscopy on Omega (Final report)

Using the 2-MeV Van de Graaf Accelerator at SUNY Geneseo's Nuclear Structure Laboratory, a {sup 3}He-implanted tantalum target was bombarded by 450-keV deuterons to produce high energy protons via the {sup 3}He(d,p){sup 4}He reaction. A 1500-{micro}m surface barrier detector with a 3/16 inch diameter collimator was placed at 8.75 cm from the target and 135{sup o} from the incident beam. A movable arm was setup so that an array of aluminum filters of varying thicknesses could be rotated in front of the detector. A 6-{micro}m mylar filter was also mounted on the movable arm and was used to calibrate the detector as described in the CR-39 experiment report. Eight aluminum filters with thicknesses ranging from 250pm to 1100{micro}m were in turn rotated in front of the collimator and spectra were taken for each. The results are shown on the attached graphs. The theoretical curve for each graph was generated using TRIM The exact energy distribution of the proton beam incident on the target was not known; because no such spectrum could be taken due to the high count rate for elastically scattered deuterons. Instead, it was assumed that the incident beam had a distribution similar to that measured through the …
Date: January 1, 2001
Creator: Fletcher, K.; Padalino, S.; Schwartz, B.; Olsen, M.; Wakeman, T. & Petrasso, R.
Object Type: Report
System: The UNT Digital Library
Analytical electron microscope study of the omega phase transformation in a zirconium-niobium alloy (open access)

Analytical electron microscope study of the omega phase transformation in a zirconium-niobium alloy

The study of the as-quenched omega phase morphology shows that the domain size of Zr-15% Nb is on the order of 30 A. No alignment of omega domains along <222>..beta.. directions was observed and samples having undergone thermal cycling in thin foil form, did not develop a long-period structure of alternating ..beta.. and ..omega.. phases below the omega transformation temperature. (FS)
Date: January 1, 1979
Creator: Zaluzec, N. J.
Object Type: Report
System: The UNT Digital Library
Analytical electron microscope study of the omega phase transformation in a zirconium--niobium alloy (open access)

Analytical electron microscope study of the omega phase transformation in a zirconium--niobium alloy

An in-situ study of the as-quenched omega phase transformation in Zr--15% Nb was conducted between the temperatures of 77 and 300/sup 0/K using analytical electron microscopy. The domain size of the omega regions observed in this investigation was on the order of 30 A, consistent with previous observations in this system. No alignment of omega domains along <222> directions of the bcc lattice was observed and in-situ thermal cycling experiments failed to produce a long period structure of alternating ..beta.. and ..omega.. phase regions as predicted by one theory of this transformation. Several techniques of microstructural analysis were developed, refined, and standardized. Grouped under the general classification of Analytical Electron Microscopy (AEM) they provide the experimentalist with a unique tool for the microcharacterization of solids, allowing semiquantitative to quantitative analysis of the morphology, crystallography, elemental composition, and electronic structure of regions as small as 20 A in diameter. These techniques have complications, and it was necessary to study the AEM system used in this work so that instrumental artifacts which invalidate the information produced in the microscope environment might be eliminated. Once these factors had been corrected, it was possible to obtain a wealth of information about the microvolume of …
Date: June 1, 1979
Creator: Zaluzec, N.J.
Object Type: Report
System: The UNT Digital Library
Destabilization of tokamak pressure-gradient driven instabilities by energetic alpha populations (open access)

Destabilization of tokamak pressure-gradient driven instabilities by energetic alpha populations

Alpha particle populations can significantly alter existing MHD in stabilities in tokamaks through kinetic effects and coupling to otherwise stable shear Alfven waves. Here we consider resonances of the trapped alpha precessional drift with both the usual ballooning mode diamagnetic frequency ({omega}{sub *i}/2) and the toroidicity induced Alfven eigenmode (TAE). This is examined for noncircular tokamaks in the high-n ballooning limit using an isotropic alpha slowing down distribution and retaining the full energy and pitch angle dispersion in the alpha drift frequency. Applying this to CIT and ITER indicates that ballooning instabilities can persist at {Beta}'s below the ideal MHD threshold. These are especially dominated by the destabilization of the TAE mode. In addition, a hybrid fluid-particle approach for simulating alpha effects on pressure-gradient driven instabilities is described. 13 refs., 6 figs.
Date: January 1, 1989
Creator: Spong, D. A.; Holmes, J. A.; Leboeuf, J. N.; Christenson, P. J. & Michigan Univ., Ann Arbor, MI (USA). Dept. of Nuclear Engineering)
Object Type: Article
System: The UNT Digital Library
High statistics study of omega$sup 0$ production at 6 GeV/c (open access)

High statistics study of omega$sup 0$ production at 6 GeV/c

The spin-projected cross sections for $omega$$sup 0$ production at 6 GeV/ c were measured in a counter-spark chamber experiment at the Zero Gradient Synchrotron of Argonne National Laboratory. Results are presented for a sample of 25,000 $omega$$sup 0$ events, and critical tests are shown for any residual background. The reaction is dominated by the s-channel natural-parity helicity one projection (rho$sub 11$ + rho/sub 1-1) dsigma/dt which shows a turnover in the forward direction and no strong dip at t = 0.6 (GeV/c)$sup 2$. The unnatural- parity helicity-zero cross section rho$sub 00$ dsigma/dt shows no forward turnover suggesting a sizeable helicity-nonflip contribution. Comparisons are made with the predictions of a Regge exchange model with absorptive corrections. (auth)
Date: January 1, 1975
Creator: Shaevitz, M.H.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Measurement of the asymmetry in the decay Antiomega+ ---> Antilambda K+ ---> anti-p pi+ K+ (open access)

Measurement of the asymmetry in the decay Antiomega+ ---> Antilambda K+ ---> anti-p pi+ K+

The asymmetry in the {bar p} angular distribution in the sequential decay {bar {Omega}}{sup +} {yields} {bar {Lambda}}K{sup +} {yields} {bar p}{pi}{sup +}K{sup +} has been measured to be {bar {alpha}}{sub {Omega}}{bar {alpha}}{sub {Lambda}} = [+1.16{+-}0.18(stat){+-}0.17(syst)]x10{sup -2} using 1.89x10{sup 6} unpolarized {bar {Omega}}{sup +} decays recorded by the Hyper CP (E871) experiment at Fermilab. Using the known value of {alpha}{sub {Lambda}}, and assuming that {bar {alpha}}{sub {Lambda}} = -{alpha}{sub {Lambda}}, {bar {alpha}}{sub {Omega}} = [-1.81{+-}0.28(stat){+-}0.26(syst)]x10{sup -2}. A comparison between this measurement of {bar {alpha}}{sub {Omega}}{bar {alpha}}{sub {Lambda}} and recent measurements of {alpha}{sub {Omega}}{alpha}{sub {Lambda}} made by HyperCP shows no evidence of a violation of CP symmetry.
Date: January 1, 2006
Creator: Lu, L. C.; Burnstein, R. A.; Chakravorty, A.; Chen, Y. C.; Choong, W. S.; Clark, K. et al.
Object Type: Article
System: The UNT Digital Library
Polarization dependence of magnetic neutron scattering (open access)

Polarization dependence of magnetic neutron scattering

The polarization dependence of magnetic neutron scattering is shown to depend on the imaginary part of the symmetric generalized susceptibility, chi/sub s//sup ..cap alpha beta../ = /sup 1///sub 2/(chi/sup ..cap alpha beta../(Q,..omega..) + chi/sup ..beta cap alpha../(Q,..omega..), as well as on the real part of the antisymmetric susceptibility, chi/sub a//sup ..cap alpha beta../ = /sup 1///sub 2/(chi/sup ..cap alpha beta../(Q,..omega..) - chi/sup ..beta cap alpha../(Q,..omega..)). The latter term contains the spin-wave contributions to the polarization-dependent scattering, along with other effects which are a consequence of the presence of a magnetic field or a spiral structure.
Date: January 1, 1976
Creator: Blume, M.
Object Type: Article
System: The UNT Digital Library
[38th Annual Greek Explosion] captions transcript

[38th Annual Greek Explosion]

Video of the 38th Annual Greek Explosion, a step show hosted by the University of North Texas in 2008.
Date: March 1, 2008
Creator: University of North Texas. Center for Media Production.
Object Type: Video
System: The UNT Digital Library
Diffraction efficiency and relative intensity of various x-ray analyzing crystals at Cu/sub K. cap alpha. / and Sn/sub K. cap alpha. / wavelengths and with two surface conditions (open access)

Diffraction efficiency and relative intensity of various x-ray analyzing crystals at Cu/sub K. cap alpha. / and Sn/sub K. cap alpha. / wavelengths and with two surface conditions

Crystals used for x-ray analysis come in many useful planes and 2d spacings with great variation in diffraction efficiency. This report compares the diffraction efficiency of 13 different crystals at two wavelengths, Cu/sub K..cap alpha../ and Sn/sub K..cap alpha../, and with two surface conditions, first with a cleaved or polished surface and second with a ground or sandblasted surface for enhanced diffraction. It is not obvious from published information how to select a crystal for best detection efficiency for a given plane or 2d spacing. The information in this report should help users select a crystal for a specific application.
Date: April 1, 1978
Creator: Sellick, B. O., Sr.
Object Type: Report
System: The UNT Digital Library
Near-Infrared Properties of Moderate-Redshift Galaxy Clusters: Halo Occupation Number, Mass-to-Light Ratios and Omega(M) (open access)

Near-Infrared Properties of Moderate-Redshift Galaxy Clusters: Halo Occupation Number, Mass-to-Light Ratios and Omega(M)

Using K-band imaging for 15 of the Canadian Network for Observational Cosmology (CNOC1) clusters we examine the near-infrared properties of moderate-redshift (0.19 &lt; z &lt; 0.55) galaxy clusters. We find that the number of K-band selected cluster galaxies within R{sub 500} (the Halo Occupation Number, HON) is well-correlated with the cluster dynamical mass (M{sub 500}) and X-ray Temperature (T{sub x}); however, the intrinsic scatter in these scaling relations is 37% and 46% respectively. Comparison with clusters in the local universe shows that the HON-M{sub 500} relation does not evolve significantly between z = 0 and z {approx} 0.3. This suggests that if dark matter halos are disrupted or undergo significant tidal-stripping in high-density regions as seen in numerical simulations, the stellar mass within the halos is tightly bound, and not removed during the process. The total K-band cluster light (L{sub 200},K) and K-band selected richness (parameterized by B{sub gc,K}) are also correlated with both the cluster T{sub x} and M{sub 200}. The total (intrinsic) scatter in the L{sub 200,K}-M{sub 200} and B{sub gc,K}-M{sub 200} relations are 43%(31%) and 35%(18%) respectively and indicates that for massive clusters both L{sub 200,K} and B{sub gc,K} can predict M{sub 200} with similar accuracy as …
Date: March 1, 2007
Creator: Muzzin, Adam; Yee, H. K. C.; Hall, Patrick B. & Lin, Huan
Object Type: Article
System: The UNT Digital Library
PROGRAM FOR CALCULATING OPTIMUM DIMENSIONS OF ALPHA RADIOISOTOPE CAPSULES EXPOSED TO VARYING STRESS AND TEMPERATURE. (open access)

PROGRAM FOR CALCULATING OPTIMUM DIMENSIONS OF ALPHA RADIOISOTOPE CAPSULES EXPOSED TO VARYING STRESS AND TEMPERATURE.

None
Date: January 1, 1967
Creator: Nichols, J.P. & Winkler, D.R.
Object Type: Report
System: The UNT Digital Library
LLE 1995 annual report, October 1994--September 1995 (open access)

LLE 1995 annual report, October 1994--September 1995

The fiscal year ending September 1995 (FY95) concluded the third year of the cooperative agreement (DE-FC03-92SF19460) with the U.S. Department of Energy (DOE). This report summarizes research at the Laboratory for Laser Energetics (LLE) and reports on the successful completion of the OMEGA Upgrade. Previous annual reports describe the OMEGA Upgrade design. The preliminary design for the system was complete in October 1989 and the detailed design started in October 1990. The original 24-beam OMEGA system was decommissioned in December 1992 as construction for the OMEGA Upgrade began. We discuss the initial performance results (p. 99) of the upgraded OMEGA laser system. All acceptance tests were completed, and we demonstrated that all 60 beams can irradiate a target with more energy and better beam balance than was required by DOE`s acceptance criteria. We are most proud that all program milestones were met or exceeded, and that the system was completed on time and on budget.
Date: January 1, 1996
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Two-stream cyclotron radiative instabilities due to the marginally mirror-trapped fraction for fustion alphas in tokamaks (open access)

Two-stream cyclotron radiative instabilities due to the marginally mirror-trapped fraction for fustion alphas in tokamaks

It is shown here that the marginally mirror-trapped fraction of the newly-born fusion alpha particles in the deuterium-tritium (DT) reaction dominated tokamak plasmas can induce a two-stream cyclotron radiative instability for the fast Alfven waves propagating near the harmonics of the alpha particle cyclotron frequency {omega}{sub c{alpha}}. This can explain both the experimentally observed time behavior and the spatially localized origin of the fusion product ion cyclotron emission (ICE) in TFTR at frequencies {omega} {approx} m{omega}{sub c{alpha}}.
Date: July 1, 1995
Creator: Arunasalam, V.
Object Type: Report
System: The UNT Digital Library
LLE 1997. Annual report, October 1996--September 1997 (open access)

LLE 1997. Annual report, October 1996--September 1997

The fiscal year ending September 1997 (FY97) concluded the fifth year of the cooperative agreement (DE-FC03-92SF19460) with the U.S. Department of Energy (DOE). This report summarizes research at the Laboratory for Laser Energetics (LLE) and is the final report for the first five years of the cooperative agreement. In September 1997, the cooperative agreement was renewed for an additional five years. We summarize our research during FY97, the operation of the National Laser Users` Facility (NLUF), and the education of high school, undergraduate, and graduate students in LLE programs. A general introduction to LLE`s experimental physics program and a report on recent results are found on pp. 161-167. This article includes a useful summary of the system`s operational capabilities and system parameters after three years of operation. Direct-drive inertial confinement fusion requires precise drive uniformity, the control of hydrodynamic instabilities during the implosion of the fusion target, and accurate target fabrication and characterization. The article summarizes a wide variety of experiments relating to direct-drive laser fusion, from high-yield implosion experiments to planar and spherical Rayleigh-Taylor experiments, laser-imprinting experiments, and laser-plasma interaction experiments. A detailed analysis of the equation of motion for an electron in a plane wave is presented beginning …
Date: January 1, 1998
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Group velocity effects in broadband frequency conversion on OMEGA. 1998 summer research program for high school juniors at the University of Rochester`s Laboratory for Laser Energetics: Student research reports (open access)

Group velocity effects in broadband frequency conversion on OMEGA. 1998 summer research program for high school juniors at the University of Rochester`s Laboratory for Laser Energetics: Student research reports

The powerful lasers needed for ICF can only produce light in the infrared wavelengths. However, the one micron wavelength produced by the neodymium glass that powers OMEGA and other lasers used for fusion research does not efficiently compress the fuel pellet. This happens because the infrared light is not well absorbed by the target, and because of the creation of suprathermal electrons. These suprathermal electrons preheat the fuel, adding extra resistance to compression. To eliminate these problems associated with longer wavelengths of light, the process of frequency converting the laser beam was invented. This process efficiently converts the initial beam to a beam which has three times the frequency and one third the wavelength. The third-harmonic beam, in the UV range, has a better absorption rate. The PV-WAVE computer program that the author has written has shown that increasing the frequency of SSD (Smoothing by Spectral Dispersion) on OMEGA to approximately 10 GHz as planned will not hurt the third harmonic generation conversion efficiency significantly. The increased bandwidth and increased frequency of SSD will make the laser beams that strike the target on OMEGA much smoother and more uniform than ever before. Therefore it is both safe and advisable to …
Date: March 1, 1999
Creator: Grossman, P.
Object Type: Report
System: The UNT Digital Library