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Electromagnetic pulse source characteristics experiment on an underground nuclear event

Description: From EMP technical meeting; Kirtland AFB, New Mexico, USA (25 Sep 1973). Under sponsorship of the Advanced Research Projects Agency, the Lawrence Livermore Laboratory conducted an EMP experiment in conjunction with an underground nuclear event. The purpose of the overall study of which this experiment was a part was to document the characteristics of EMP signals generated by various underground nuclear events to provide checks for theoretical models under development. A major goal was to establish how a specific event configuration affects the signals generated. For this experiment, two separate EMP source mechanisms were considered: that due to an asymmetric gamma ray distribution resulting from shielding and configuration constraints in the vicinity of the device and that due to current induced on the line-of-sight pipe. The instrumentation was not ideally located to sort out the two mechanisms because of significant differences between the planned and as-fired configuration. Nevertheless, signals characteristic of the two mechanisms seem to be apparent in the data. An impulsive (10 MHz) component of the signal is probably a result of the asymmetric gamma distribution. A ringing component (1 MHz) has been attributed to currents on the line-of- sight pipe. (auth)
Date: October 22, 1973
Creator: Knapp, M.W. & Bailey, N.D.
Partner: UNT Libraries Government Documents Department

A source for quantum control: generation and measurement of attosecond ultraviolet light pulses

Description: This project has pursued the possibility of producing ultra-short pulses of coherent light using harmonic conversion of a mid-infrared light source, focused into an atomic gas medium. This was a joint effort with Louis DiMauro's experimental group at Brookhaven National Laboratory and in collaboration with Ken Schafer from Louisiana State University and Mette Gaarde from Lund University on the theoretical part. High order harmonic generation (HHG) in nobel gas media using short-pulse visible and near infrared lasers has become an established method for producing coherent, short pulse radiation at wavelengths from the ultraviolet to soft x-rays. We recently proposed that this approach could lead to extremely short pulses, potentially less than one fs, provided the unavoidable frequency chirp of the highest harmonics, could be removed by compressing the pulses with a grating pair. Sources of sub-fs pulses would provide unique opportunities to study dynamical processes on time scales short compared to those associated with nuclear motion. Truly stroboscopic pictures of chemical reaction dynamics would be possible, for example. In this research project we have chosen much smaller driving frequencies than used previously in HHG studies for two reasons. First, this will allow us to measure the pulse lengths of the compressed harmonics because they will be in the vacuum ultraviolet where coincidence measurements are possible. Second, the wavelengths of these harmonics will be idea for pump-probe experiments of quantum dynamical control studies. Our theoretical effort was concentrated in two areas. We used our time-dependent quantum numerical codes to evaluate the harmonic response of alkali atoms to the mid-IR laser excitation. Results were obtained for potassium, the initial species to be used in the experiments, then sodium and rubidium to investigate the possibility of higher conversion efficiencies. In fact, rubidium was found to be significantly better than potassium, both because it ...
Date: February 19, 1999
Creator: Kulander, K C
Partner: UNT Libraries Government Documents Department

Evolution of Rydberg states in half-cycle pulses: Classical, semiclassical, and quantum dynamics

Description: We summarize recent theoretical advances in the description of the evolution of Rydberg atoms subject to ultrashort pulses extending only a fraction of an optical cycle. We have performed classical. semiclassical and full quantum calculations in order to delineate the classical-quantum correspondence for impulsively perturbed atomic systems. We observe classical and quantum (or semiclassical) oscillations in excitation and ionization which depend on the initial state of atoms and on the strength of the perturbation. These predictions can be experimentally tested. 4 figs.
Date: December 31, 1994
Creator: Burgdoerfer, J. & Reinhold, C.
Partner: UNT Libraries Government Documents Department

Observation of ionization instability of intense laser pulses

Description: Theoretical analysis and preliminary experiment on ionization instability of intense laser pulses in ionizing plasmas are presented. The ionization instability is due to the dependence of the ionization rate on the laser intensity and scatters the laser energy off the original propagation direction.
Date: June 25, 1999
Creator: Alexeev, I; Antonsen, T M; Li, Y; Milchberg, H M & Nikitin, S
Partner: UNT Libraries Government Documents Department

A System for Measuring Energy and Peak Power of Low-Level 1.064 [mu]m Laser Pulses

Description: From introduction: For the first time, transfer standards have been developed for measuring 1.064 Pm laser pulses of duration about 10-100 ns, peak irradiance of about 10-8-10-4 W/cm2, and fluences of about 10-16-10-11 J/cm2 . These energy and power measurement devices use PIN and APD silicon detectors, respectively, and can be used as stable transfer standards with total uncertainties (random errors computed at the 95 percent confidence level) of 10 to 15 percent. The system for calibrating these transfer standards is also described and consists of a cw Nd:YAG laser beam acousto-optically modulated to provide low-level laser pulses of known peak power and energy. A detailed evaluation of systematic and random errors is also shown.
Date: October 1982
Creator: Sanders, A. A. & Rasmussen, A. L.
Partner: UNT Libraries Government Documents Department


Description: Progress is reported in assembling available unclassified flooding data in perforated-plate pulsed extraction columns through January 1, 1963. Existing correlations are critically reviewed, and recommendations are made to develop a better flooding correlation. (auth)
Date: June 1, 1963
Creator: McAllister, R.A. & Ryon, A.D.
Partner: UNT Libraries Government Documents Department

The use of fractally-designed waveforms in electroforming

Description: Pulsed electrodeposition offers the potential for superior control of deposit properties because of the additional control variables available. However, optimization of pulsed deposition processes is a challenge because of the complexity. E.g., the tendency of electroforms to acquire irregularities such as dendritic growths or other morphological instabilities, creates the need for methods to control these undesirable phenomena. One such method is periodic reverse pulses. Optimization of periodic reverse processes is not simple and can lead to local solutions that do not optimize all properties simultaneously. One method for global optimization that might, for example, control surface irregularities on several size scales, uses a periodic reverse design based on fractal time series. This incorporates deplating pulses of several lengths within one self- similar waveform. The properties of fractals permit control of highly complex designs with a small number of input variables. The creation of such waveforms, their properties, and their use in a lead- plating process are described. Speculation on the potential for further application of this method is offered. 26 figs, 11 refs.
Date: March 1, 1996
Creator: Bullock, J.S.; Lawson, R.L. & Kirkpatrick, J.R.
Partner: UNT Libraries Government Documents Department

Electromagnetic targeting of guns

Description: This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Electromagnetic pulse (EMP) signals produced from explosives being fired have been reported in the literature for fifty years. When a gun is fired it produces an EMP muzzle blast signal. The strength and nature of these signals was first analyzed in the early 1970s, while the results were interesting, no follow-up studies were conducted. With modern detection and signal processing technology, we believe that these signals could be used to instantaneously locate guns of virtually all calibers as they fire. The objective of our one-year project was to establish the basic nature of these signals and their utility in the concept of electromagnetic targeting of guns.
Date: October 1, 1996
Creator: Pogue, E.W.; Boat, R.M.; Holden, D.N. & Lopez, J.R.
Partner: UNT Libraries Government Documents Department

Femtosecond laser postionization of sputtered and laser desorbed atoms

Description: This paper examines the photoionization efficiency of a femtosecond laser ionization source on several atomic species. Use of femtosecond laser ionization pulses to photoionize the desorbing flux from a sample surface is examined. Example of mass spectra produced is given using 248 nm pulse on sputtered Au. Al and Mo have widely different ionization potentials and show that 248 nm pulses are more efficient at photoionization than longer wavelengths; this is enhanced for Mo with high ionization potential. It is concluded that efficient photoionization occurs for atoms with ionization potentials low enough for two-photon ionization to occur.
Date: June 1, 1995
Creator: Pellin, M.J.; Lykke, K.R. & Calaway, W.F.
Partner: UNT Libraries Government Documents Department


Description: A series of pilot plant runs was conducted to define new cartridges for increasing the capacity in the Purex 1 Bx, 2A, lC and 2E columns and eliminate plastic cartridge failures in the HA column scrub section, the HS column and the 2A column. The most favorable designs are presented and data from the various runs are included. (J.R.D.)
Date: February 22, 1961
Creator: Jansen, G. & Richardson, G.L.
Partner: UNT Libraries Government Documents Department


Description: The papers presented at the meeting were recorded and transcripts are given along with the discussion which followed each paper. Separate abstracts were prepared for 12 of the 13 papers presented. (W.D.M.)
Date: October 31, 1960
Partner: UNT Libraries Government Documents Department