2007 DPP Meeting
DPP 2007 Meeting Abstracts
Noble Gas Analysis for the OMEGA Gas Sampling System
G.T. Young, S.M. Hupcher, C.G. Freeman; SUNY Geneseo
M.A. Stoyer; Lawrence Livermore National Laboratory
T.C. Sangster; Laboratory for Laser Energetics
The OMEGA Gas Sampling System (OGSS) at the Laboratory for Laser Energetics can be used to study a wide variety of implosion parameters in inertial confinement fusion. By doping a target capsule with carefully chosen detector nuclei, nuclear reactions between fusion products and detector nuclei can produce noble gas isotopes. Following a capsule implosion, these gases are pumped out of the target chamber and are collected into sample bottles. We have developed a bench-top analysis station at Geneseo capable of determining the number of noble gas atoms present in the sample bottles. A needle valve is used to admit gas from the sample bottles into a vacuum chamber at a controlled rate. The conductance of the needle valve is a function of pressure and gas type. A residual gas analyzer (RGA) is used to measure the partial pressures of each type of noble gas in the vacuum chamber. The RGA is calibrated with a calibrated leak, which allows known amounts of different gases into the chamber at a constant rate. Analysis of the gasses collected following a D3He implosion is currently underway.
*Funded in part by a grant from the DOE through the Lab for Laser Energetics
Preparation of Deuterated Polymer Targets for the OMEGA Magnetic Recoil Spectrometer
Jacqueline Strain, Gerald Rawcliffe, Joseph Katz, Kurtis Fletcher; SUNY Geneseo
Johan Frenje; Plasma Science and Fusion Center, MIT
Sean MacMullin; UNC Chapel Hill
Uniform deuterated polymer films on tantalum substrates are used as targets for the new Magnetic Recoil Spectrometer (MRS) at the OMEGA laser system at the University of Rochester's Laboratory for Laser Energetics. The MRS is designed to measure the neutron energy spectrum produced in inertial confinement fusion (ICF) experiments by detection of deuterons elastically scattered from the polymer target. The goal of our project is to produce circular films with areas ranging from 2 to 15 cm2 and thicknesses ranging from 40 to 300 microns. Design parameters stipulate that the polymer thicknesses must be characterized to within 5% with less than 5% variation throughout the sample. Methods for preparing and characterizing these films will be discussed.
*Funded in part by a grant from the DOE through the Lab for Laser Energetics
First Measurements of Neutron Spectra using the Magnetic Recoil Spectrometer (MRS) at OMEGA
J. A. Frenje, D. Casey, C.K. Li, J. Rygg, F.H. Seguin, R.D. Petrasso; MIT PSFC
V. Yu. Glebov, D.D. Meyerhofer, T.C. Sangster; UR LLE
K. Fletcher; SUNY Geneseo
A new type of neutron spectrometer, a Magnetic Recoil Spectrometer (MRS), is being implemented at OMEGA for measurements of the scattered-DT-neutron spectrum, from which ?R can be inferred. Implementing an MRS at OMEGA is important for several reasons. First, it allows comprehensive tests of the different MRS parameters. Second, ?R of cryogenic DT implosions can be inferred from both the MRS and charged-particle spectrometry for moderate ?R implosions (?R<200 mg/cm2); this allows for a definitive check of the MRS. Third, as there is no other way to determine ?R when it exceeds 200 mg/cm2, the MRS will bring a required diagnostic to the OMEGA cryogenic program. Fourth, the experience with MRS implementation and resulting neutron data at OMEGA will enable us to implement an optimal MRS for the NIF. The results from the first MRS measurements performed at OMEGA are presented.
*This work was supported in part by U.S. DOE, LLE and LLNL.
Impact of Cryogenic Temperatures on the Mechanical Properties of Steatoda Triangulosa Spider Silk
Edward Pogozelski, Brendan See, Christina Kieffer, William Becker, Stephen Padalino; SUNY Geneseo
Craig Sangster; Laboratory for Laser Energetics
The mechanical properties of dragline spider silk from the species Steatoda Triangulosa are examined at 77K. Dragline silk is used as a structural material to support deuterium - tritium laser fusion targets at the Laboratory for Laser Energetics (LLE) in Rochester, NY. As the targets are filled, the dragline is exposed to cryogenic temperatures. To simulate this environment, silk is dipped into liquid nitrogen. The strength, toughness, and modulus of elasticity of silk in liquid nitrogen are compared to these properties in air. Cryogenic dragline is 200% as strong, 125% as tough, and has an elastic modulus of 300% compared to silk in air at room temperature.
*Funded in part by a grant from the DOE through the Lab for Laser Energetics
VELoCiRaPTORS
J. Lundgren, B. Esham, S.J Padalino; SUNY Geneseo
T.C. Sangster, V. Glebov; Laboratory for Laser Energetics
The Venting and Exhausting of Low Level Air Contaminants in the Rapid Pneumatic Transport of Radioactive Samples (VELoCiRaPTORS) system is constructed to transport radioactive materials quickly and safely at the NIF. A radioactive sample will be placed inside a carrier that is transported via an airflow system produced by controlled differential pressure. Midway through the transportation process, the carrier will be stopped and vented by a powered exhaust blower which will remove radioactive gases within the transport carrier. A Geiger counter will monitor the activity of the exhaust gas to ensure that it is below acceptable levels. If the radiation level is sufficient, the carrier will pass through the remainder of the system, pneumatically braking at the counting station. The complete design will run manually or automatically with control software. Tests were performed using an inactive carrier to determine possible transportation problems. The system underwent many consecutive trials without failure. VELoCiRaPTORS is a prototype of a system that could be installed at both the Laboratory for Laser Energetics at the University of Rochester and the National Ignition Facility at LLNL.
*Funded in part by a grant from the DOE through the Lab for Laser Energetics
Elemental Analysis of Carbon Disks using Proton Induced X-ray Emission
Melissa Cummings, Kelly Donovan, Stephen Padalino; SUNY Geneseo
Vladimir Glebov, T. Craig Sangster; Laboratory for Laser Energetics
An experimental method for determining the ?R and (?R)2 of high energy-density inertial confinement fusion targets has been developed, which involves measuring the yield of tertiary neutrons with energies higher than 20 MeV. Carbon activation is a suitable technique for this measurement due to its high energy neutron reaction threshold and the availability of ultra high-purity samples at a relatively low cost. The tertiary neutron yield is more than six orders of magnitude lower than the primary neutron yield, so ultra pure carbon samples that are free from any positron-emitting contaminants are essential to this diagnostic. The goal of this project was to use proton induced x-ray emission (PIXE) as a technique for determining trace amounts of contaminant elements in the carbon disks. *Funded in part by a grant from the DOE through the Lab for Laser Energetics Measuring Positron Annihilation in NaI(Tl) Detectors as the Final Stage in a Carbon Diagnostic
Measuring Positron Annihilation in NaI(Tl) Detectors as the Final Stage in a Carbon Diagnostic
Melissa Cummings, Kelly Donovan, Stephen Padalino; SUNY Geneseo
Vladimir Glebov, T. Craig Sangster; Laboratory for Laser Energetics
This study was performed to increase the detection efficiency of 511 keV annihilation radiation from decaying C-11 by identifying and eliminating different forms of background radiation originating from the source and the ambient background in the gamma ray coincidence spectrum. Cu-64 was substituted for C-11 in this investigation since it could be easily made from Cu-63 via neutron capture using a PuBe neutron source. Using Cu-64, the effect of ambient background and source induced radiation in the NaI detectors was examined in three coincidence spectra. The spectra were generated by pairing the output signals of the three NaI(Tl) detectors and displaying them as two dimensional spectra. Different gamma ray background contributions to the coincidence spectrum were studied, including annihilation radiation from pair production in the detectors and the lead shielding. Detector geometries and source materials which modified the Compton scattering background were also investigated.
*Funded in part by a grant from the DOE through the Lab for Laser Energetics
Modeling a Carbon Diagnostic System Using MCNPX
S.H. Fay, C.M. Kuhn, E.E. Smith, S.L. Stephenson; Gettysburg College
T.C. Sangster, V. Glebov; Laboratory for Laser Energetics
S.J. Padalino; SUNY Geneseo
Monte-Carlo N-Particle Extended (MCNPX) is currently being used to model various carbon diagnostic configurations for use at OMEGA with plans to design a similar system for the NIF. The purpose of such models is to optimize the carbon diagnostic's detection of signature products (i.e. tertiary neutrons) from a self-sustaining inertial confinement fusion (ICF) implosion. Results will be presented.
*Funded in part by a grant from the U.S. DOE.
Plasma Physics Research at an Undergraduate Institution
Stephen Padalino; SUNY Geneseo
Undergraduate research experiences have motivated many physics majors to continue their studies at the graduate level. The Department of Physics and Astronomy at SUNY Geneseo, a primarily undergraduate institution, recognizes this simple reality and is committed to ensuring research opportunities are available to interested majors beginning as early as their freshman year. Every year for more than a decade, as many as two dozen students and 8 faculty members have worked on projects related to high energy density physics and inertial confinement fusion during the summer months and the academic year. By working with their research sponsors, it has been possible to identify an impressive number of projects suitable for an institution such as Geneseo. These projects tend to be hands-on and require teamwork and innovation to be successful. They also take advantage of in-house capabilities such as the 2 MV tandem pelletron accelerator, a scanning electron microscope, a duoplasmatron ion deposition system and a 64 processor computing cluster. The end products of their efforts are utilized at the sponsoring facilities in support of nationally recognized programs. In this talk, I will discuss a number of these projects and point out what made them attractive and appropriate for an institution like Geneseo, the direct and indirect benefits of the research opportunities for the students and faculty, and how the national programs benefited from the cost-effective use of undergraduate research. In addition, I will discuss the importance of exposure for both students and faculty mentors to the larger scientific community through posters presentations at annual meetings such as the DPP and DNP. Finally, I will address the need for even greater research opportunities for undergraduate students in the future and the importance of establishing longer "educational pipelines" to satisfy the ever growing need for top-tier scientists and engineers in industry, academia and the national laboratories.