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1.
Europium (Eu+) ions were confined in a Paul trap and detected by non-destructive method. Storage time of Eu+ ions achieved in vacuum was improved by orders of magnitude employing buffer gas cooling. The experimentally detected signal
was fitted to the ion response signal and the total number of ions trapped was estimated. It is found that the peak signal
amplitude as well as the product of FWHM and the peak signal amplitude is proportional to the total number of trapped ions.
The trapped ion secular frequency was swept at different rates and its effect on the absorption line profile was studied both
experimentally and theoretically. 相似文献
2.
Davis J. Clark R.W. Giuliani J.L. Jr. Thornhill J.W. Deeney C. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1998,26(4):1192-1201
In this paper, we study the dynamics of a massive aluminum Z-pinch plasma load and evaluate its performance as a soft X-ray radiator. A radiation hydrodynamic model self-consistently driven by a circuit describes the dynamics. Comparisons are made for the K- and L-shell soft X-ray emission as a function of the ionization dynamic model. The ionization dynamic models are represented by: 1) a time-dependent nonequilibrium (NEQ) model, 2) a collisional radiative equilibrium (CRE) model, and 3) a local thermodynamic equilibrium (LTE) model. For all three scenarios the radiation is treated 1) in the free streaming optically thin approximation where the plasma is treated as a volume emitter and 2) in the optically thick regime where the opacity for the lines and continuum is self-consistently calculated online and the radiation is transported through the plasma. Each simulation is carried out independently to determine the sensitivity of the implosion dynamics to the ionization and radiation model, i.e., how the ionization dynamic model affects the radiative yield and emission spectra. Results are presented for the L- and K-shell radiation yields and emission spectra as a function of photon energy from 10 eV to 10 keV. Also, departure coefficients from LTE are presented for selected levels and ionization stages 相似文献
3.
Sanford TW Allshouse GO Marder BM Nash TJ Mock RC Spielman RB Seamen JF McGurn JS Jobe D Gilliland TL Vargas M Struve KW Stygar WA Douglas MR Matzen MK Hammer JH De Groot JS Eddleman JL Peterson DL Mosher D Whitney KG Thornhill JW Pulsifer PE Apruzese JP Maron Y 《Physical review letters》1996,77(25):5063-5066
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Deeney C Apruzese JP Coverdale CA Whitney KG Thornhill JW Davis J 《Physical review letters》2004,93(15):155001
Nested-wire array experiments have been conducted at the 7 MA level with 150 ns implosion times from an outer diameter of 40 mm. Analysis of spectral data indicates that material from the outer array preferentially occupies the high temperature core of the stagnated pinch independent of the interwire gap in the range of 1.1 to 4.5 mm. 相似文献
6.
Rudakov LI Velikovich AL Davis J Thornhill JW Giuliani JL Deeney C 《Physical review letters》2000,84(15):3326-3329
In numerous experiments, magnetic energy coupled to strongly radiating Z-pinch plasmas exceeds the thermalized kinetic energy, sometimes by a factor of 2-3. We demonstrate that the enhanced energy coupling may be due to the buoyancy rise of toroidal magnetic flux tubes converging to the axis through the unstable pinch plasma. We derive an explicit formula for the enhanced dissipation rate and apply this formula to reconsider an old problem of power balance in a steady-state Z pinch, and then to analyze a new challenge of producing K-shell 3 to 10 keV radiation in long-pulse Z-pinch implosions. 相似文献
7.
A theoretical procedure for estimating the precision of the T(1) Fast Acquisition Relaxation Mapping sequence as a function of a number of acquisition parameters has been validated by both simulations and experimental results. These results have clarified the selection of sequence parameters to give optimal accuracy and precision in the R(1)* measurements. There is excellent agreement between theory, simulation, and experiment except for flip angles greater than 9 degrees, at which point slice profile imperfections significantly degrade the precision of the technique. The experimental results indicate that over a range of T(1)s that would be seen in a bolus tracking experiment (25-1200 ms), T(1) Fast Acquisition Relaxation Mapping can be used to obtain 64 x 128 R(1)* maps at a rate of 1 map/s, with a precision of 10% or better. 相似文献
8.
Particle image velocimetry is used to study the motion of gas within a duct subject to the passage of a finite amplitude pressure wave. The wave is representative of the pressure waves found in the exhaust systems of internal combustion engines. Gas particles are accelerated from stationary to 150 m/s and then back to stationary in 8 ms. It is demonstrated that gas particles at the head of the wave travel at the same velocity across the duct cross section at a given point in time. Towards the tail of the wave viscous effects are plainly evident causing the flow profile to tend towards parabolic. However, the instantaneous mean particle velocity across the section is shown to match well with the velocity calculated from a corresponding measured pressure history using 1D gas dynamic theory. The measured pressure history at a point in the duct was acquired using a high speed pressure transducer of the type typically used for engine research in intake and exhaust systems. It is demonstrated that these are unable to follow the rapid changes in pressure accurately and that they are prone to resonate under certain circumstances. 相似文献
9.
Eliene O Kozlowski Paula C Lima Cristina P Vicente Tito Lotufo Xingfeng Bao Kazuyuki Sugahara Mauro SG Pavão 《BMC biochemistry》2011,12(1):1-2
After the publication of the work entitled "Dermatan sulfate in tunicate phylogeny: Order-specific sulfation pattern and the effect of [→4IdoA(2-Sulfate)β-1→3GalNAc(4-Sulfate)β-1→] motifs in dermatan sulfate on heparin cofactor II activity", by Kozlowski et al., BMC Biochemistry 2011, 12:29, we found that the legends to Figures 2 to 5 contain serious mistakes that compromise the comprehension of the work. This correction article contains the correct text of the legends to Figures 2 to 5. 相似文献
10.
Amino acid separation on SE-Sephadex C-25 总被引:1,自引:0,他引:1