The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Protein-protein interactions (PPIs) are vital for cell signaling, protein trafficking and localization, gene expression, and many other biological functions. Rational modification of PPI targets provides a mechanism to understand their function and importance. However, PPI systems often have many more degrees of freedom and flexibility than the small-molecule binding sites typically targeted by protein...
We have reestablished gas puff z-pinch capability on Sandia's 20 MA Z machine, including a Sandia-operated driver system and an imaging interferometer to characterize nozzle mass flow [1]. Initial experiments have focused on developing a 3 keV Ar K-shell x-ray source. We have pursued a design-driven approach to planning these experiments, utilizing numerical simulation to predict Ar K-shell yield...
Short burst, ultrafast laser pulses interact intensely with matter to generate beams of secondary radiation such as coherent x-rays via high harmonic generation, electron bunches via laser wakefield acceleration, and protons via laser-driven ion acceleration. These secondary radiation sources have applications in biological imaging, medical diagnostics and treatment, and nondestructive evaluation...
A variety of plasma applications make use of pulsed gas jets. In some cases like a z-pinch1, one requirement is for cylindrical symmetry in the mass distribution delivered by a nozzle system. In other cases like astrophysical simulations2 or laser wakefield accelerators (LWA)3, controlled asymmetry is desired. Hence there is a need for diagnostic methods to assess the 3D geometry of the cold gas flow...
The formation of highly supersonic, radiatively cooled plasma jets with applications to laboratory astrophysics has been an active area of research on the MAGPIE generator. Two experimental arrangements, radial wire arrays1 and radial foils2, can produce plasma flows with similar dimensionless numbers to those encountered in protostellar jets. In radial wire arrays, a magnetically driven jet on the...
Summary form only given. Poor initiation could be the reason that some plasma focus devices show a poor reproducibility shot to shot. A recent publication by Verma et al suggests that operating a small plasma focus at higher repetition rates increase the neutron yield for a given stored energy by as much as 10 x. It is hypothesized that the residual ionization from one pinch helps better initiate...
Summary form only given. This paper presents initial designs of multiple-shell gas puff imploding loads for the refurbished Z generator. The nozzle has three independent drivers for three independent plena. The outer and middle plena may be charged to 250psia whilst the central jet can be charged to 1000psia. 8-cm and 12-cm outer diameter nozzles have been built and tested on the bench. The unique...
In this paper, we describe a scheme for tolerating and recovering from mid-query faults in a distributed shared nothing database. Rather than aborting and restarting queries, our system, Osprey, divides running queries into subqueries, and replicates data such that each subquery can be rerun on a different node if the node initially responsible fails or returns too slowly. Our approach is inspired...
Pulsed neutron accelerators have been considered for active interrogation of special nuclear materials and also for location and imaging of explosives using PFNA. Alameda Applied Sciences Corporation is developing a <40 ns pulsed neutron source for these applications, based on the dense plasma focus (DPF). The Dense Plasma Focus (DPF) produces a 10-40 ns (FWHM) neutron pulse, with output scaling...
Summary form only given. The Dense Plasma Focus (DPF) produces a 10-40 ns (FWHM) neutron pulse, with output scaling as I4 over a wide range (~10 kA-1 MA) of peak current (I). Typical neutron yield per pulse is 106 n/pulse at ~100 kA, scaling to ~108 n/pulse at ~300 kA. It is well known that the neutron output from a DPF is due to a combination of thermal fusion along with so-called beam-target fusion,...
Summary form only given. The Dense Plasma Focus (DPF) is a versatile source of soft x-ray and neutron emission, for calibration purposes. This paper describes results from a 500J/130kA and a 2kJ/300kA DPF, operated at 0.2-2Hz rep-rates. Using the five-phase, Sing Lee1 model of the DPF, optimized head designs were tested with Deuterium, Neon and Argon gas fills. The 20- 40ns FWHM neutron output was...
We present results from the first wire array experiments performed on a new 250 kA linear transformer driver (LTD) generator installed at UCSD. The LTD design represents a new approach in the field of exploding wire experiments. Importantly this driver creates the opportunity for repetition-rated experiments, which are unfeasible for traditional Marx driven systems. We will discuss the design of the...
This paper presents a dynamical study of vacuum gap formation in X-pinch plasmas at 80 kA pulsed power generator. Diagnostics include multiple frame laser interferometry to recover quantitative information, as well data from X-ray diodes, laser Schlieren imaging, time-integrated X-ray pinhole cameras, and a gated XUV framing camera. The velocity with which the gap opens can be determined from laser...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.