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S Chawla  One of the best experts on this subject based on the ideXlab platform.

effect of Target Material on relativistic electron beam transport
Physics of Plasmas, 2019CoAuthors: S Chawla, M S Wei, H S Mclean, P K Patel, M Baillygrandvaux, F N BegAbstract:A computational study using the hybridparticleincell code ZUMA investigated the transport of a fast electron beam (55 J, 1013 A/cm2) produced at Titan laser conditions (λ = 1 μm, 0.7 ps, 1020 W/cm2) in Materials ranging from the low to high atomic number, specifically fast electron stopping and the evolution of resistive magnetic fields. Fast electron energy loss due to stopping was similar in Al, Cu, and Ag (21%–27%) and much higher in Au (54%). Ohmic stopping was found to dominate over collisional stopping in all Materials except Au. Resistive magnetic field growth was shown to depend on the dynamic competition between the resistivity and resistivity gradient source terms in Faraday's Law. Moreover, the dependence of these terms on the background Material ionization state and temperature evolution is presented. The advantages of midZ Materials for collimation are discussed, as well as the implications for collimation at fast ignition conditions.

effect of Target Material on fast electron transport and resistive collimation
Physical Review Letters, 2013CoAuthors: S Chawla, M S Wei, R Mishra, K U Akli, C D Chen, H S Mclean, A Morace, P K PatelAbstract:The effect of Target Material on fastelectron transport is investigated using a highintensity (0.7 ps, ${10}^{20}\text{ }\text{ }\mathrm{W}/{\mathrm{cm}}^{2}$) laser pulse irradiated on multilayered solid Al Targets with embedded transport (Au, Mo, Al) and tracer (Cu) layers, backed with millimeterthick carbon foils to minimize refluxing. We consistently observed a more collimated electron beam (36% average reduction in fastelectron induced Cu $K\ensuremath{\alpha}$ spot size) using a high or mid$Z$ (Au or Mo) layer compared to Al. All Targets showed a similar electron flux level in the central spot of the beam. Twodimensional collisional particleincell simulations showed formation of strong selfgenerated resistive magnetic fields in Targets with a high$Z$ transport layer that suppressed the fastelectron beam divergence; the consequent magnetic channels guided the fast electrons to a smaller spot, in good agreement with experiments. These findings indicate that fastelectron transport can be controlled by selfgenerated resistive magnetic fields and may have important implications to fast ignition.
Takafumi Matsui  One of the best experts on this subject based on the ideXlab platform.

effects of Target Material properties on transient crater growth
Lunar and Planetary Science Conference, 2008CoAuthors: S Yamamoto, Seiji Sugita, Takafumi MatsuiAbstract:Introduction: It has been reported that even in the gravity regime, a scaling relation of impact cratering may depend on Target Material properties, such as porosity or the angle of repose [e.g. 1, 2]. However, it is unknown how Target Material properties are related to the scaling relation. In order to investigate this issue, we need direct observation of transient crater growth. From our recent observations of a temporal change in diameter of a crater cavity (hereafter, diameter growth)[3, 4], we found that the rate of increase in diameter of a crater cavity at early times follows a powerlaw relation, but the rate of increase at late times deviates from the powerlaw relation. In addition, the powerlaw exponent at early times and the degree of the deviation from a powerlaw (hereafter, the degree of deviation) at later times were shown to depend on Target Material properties [4]. Thus, in order to formulate a scaling relation taking into account Target Material properties, we need to investigate quantitatively how the powerlaw exponent and the degree of deviation are related to Target Material properties. In this study, we thus measured the powerlaw exponent and the degree of deviation for various Targets. Experiment: We used the following five Targets: sodalime glass spheres whose mean diameters are 36 μm, 220 μm, and 1.2 mm (hereafter they are referred as TA, TC, and TE Targets, respectively), dry sand with mean diameter of 300 μm, and liquid water. The porosity and the angle of repose for these Targets are listed in Table 1. Polycarbonate projectiles (10 cm in diameter and 0.49 g in mass) were impacted vertically into a Target by a singlestage lightgas gun. We measured the diameter growth as follows: for sodalime glass and dry sand Targets, we used the laser method [3, 4] in which a vertical lasersheet illuminates the Target at the impact site, and the temporal change of a laser line on the Target surface during the transient crater growth is observed by a highspeed video camera set above the Target. From the shape of the laser line, we can estimate the diameter of a crater cavity at each time step. For water Target, we measured directly the diameter of a crater cavity through a transparent Target container by the camera [see, 5]. All the experiments were conducted under the condition with the ambient pressures <50 Pa (glass sphere and dry sand Targets) or <2000 Pa (water Target). Analysis: Fig. 1 shows an example of the diameter growth (this is the case of TA Target). We can see that the data at early times (<~0.01 s) follows a powerlaw, but the data at late times deviates from the powerlaw. We determined the powerlaw exponent and the degree of deviation as follows: In our previous study [4], we proposed the following model to explain the diameter growth: In Maxwell’s Zmodel [6], the radial component of the excavation flow velocity ur at the distance r is given as ur=α(t)/r, where Z is a constant and α(t) is a function of the time t. When we assume α(t)∝e, the diameter d(t) of a crater cavity is derived as: d(t) ∝ (1e) γ , ... (1) where β is a constant and a powerlaw exponent γ =1/(Z+1). This equation can represent well the data of diameter growth, as shown in Fig. 1 (red solid curve). Since the values of γ and β correspond to the powerlaw exponent and the degree of deviation, respectively [4], we can use γ and β to study quantitatively how the powerlaw exponent and the degree of deviation are related to Target Material properties.

transient crater growth in granular Targets an experimental study of low velocity impacts into glass sphere Targets
Icarus, 2006CoAuthors: Satoru Yamamoto, Norihisa Okabe, Koji Wada, Takafumi MatsuiAbstract:Abstract We experimentally studied the formation and collapse processes of transient craters. Polycarbonate projectiles with mass of 0.49 g were impacted into the sodalime glass sphere Target (mean diameters of glass spheres are ∼36, 72, and 220 μm, respectively) using a singlestage lightgas gun. Impact velocity ranged from 11 to 329 m s−1. We found that the transient crater collapses even at laboratory scales. The shape (diameter and depth) of the transient crater differs from that of the final crater. The depth–rim diameter ratios of the final and transient craters are 0.11–0.14 and 0.26–0.27, respectively. The rim diameter of both the transient and final crater depends on Target Material properties; however, the ratio of final to transient crater diameter does not. This suggests that Target Material properties affect the formation process of transient craters even in the gravity regime, and must be taken into account when scaling experimental results to planetary scales. By observing impacts into glass sphere Targets, we show that although the early stage of the excavation flow does not depend on the Target Material properties, the radial expansion of the cavity after the end of vertical expansion does. This suggests that the effect of Target Material properties is specifically important in the later part of the crater excavation and collapse.
P K Patel  One of the best experts on this subject based on the ideXlab platform.

effect of Target Material on relativistic electron beam transport
Physics of Plasmas, 2019CoAuthors: S Chawla, M S Wei, H S Mclean, P K Patel, M Baillygrandvaux, F N BegAbstract:A computational study using the hybridparticleincell code ZUMA investigated the transport of a fast electron beam (55 J, 1013 A/cm2) produced at Titan laser conditions (λ = 1 μm, 0.7 ps, 1020 W/cm2) in Materials ranging from the low to high atomic number, specifically fast electron stopping and the evolution of resistive magnetic fields. Fast electron energy loss due to stopping was similar in Al, Cu, and Ag (21%–27%) and much higher in Au (54%). Ohmic stopping was found to dominate over collisional stopping in all Materials except Au. Resistive magnetic field growth was shown to depend on the dynamic competition between the resistivity and resistivity gradient source terms in Faraday's Law. Moreover, the dependence of these terms on the background Material ionization state and temperature evolution is presented. The advantages of midZ Materials for collimation are discussed, as well as the implications for collimation at fast ignition conditions.

effect of Target Material on fast electron transport and resistive collimation
Physical Review Letters, 2013CoAuthors: S Chawla, M S Wei, R Mishra, K U Akli, C D Chen, H S Mclean, A Morace, P K PatelAbstract:The effect of Target Material on fastelectron transport is investigated using a highintensity (0.7 ps, ${10}^{20}\text{ }\text{ }\mathrm{W}/{\mathrm{cm}}^{2}$) laser pulse irradiated on multilayered solid Al Targets with embedded transport (Au, Mo, Al) and tracer (Cu) layers, backed with millimeterthick carbon foils to minimize refluxing. We consistently observed a more collimated electron beam (36% average reduction in fastelectron induced Cu $K\ensuremath{\alpha}$ spot size) using a high or mid$Z$ (Au or Mo) layer compared to Al. All Targets showed a similar electron flux level in the central spot of the beam. Twodimensional collisional particleincell simulations showed formation of strong selfgenerated resistive magnetic fields in Targets with a high$Z$ transport layer that suppressed the fastelectron beam divergence; the consequent magnetic channels guided the fast electrons to a smaller spot, in good agreement with experiments. These findings indicate that fastelectron transport can be controlled by selfgenerated resistive magnetic fields and may have important implications to fast ignition.
Marc C. Fivel  One of the best experts on this subject based on the ideXlab platform.

cavitation erosion using the Target Material as a pressure sensor
Journal of Applied Physics, 2015CoAuthors: Jeanpierre Franc, Marc C. FivelAbstract:Numerical prediction of mass loss due to cavitation erosion requires the knowledge of the hydrodynamic impact loads generated by cavitation bubble collapses. Experimental measurements of such impact loads using conventional pressure sensors are not reliable (if not impossible) due to the micron size and the very small duration of the loading. In this paper, a new method to estimate these loading conditions is proposed based on cavitation pitting tests and an iterative inverse finite element modeling. The principle of the method is as follows. First, numerous pits corresponding to localized plastically deformed regions are identified from a cavitation test performed in a dedicated tunnel. Then each pit is numerically reproduced by finite element simulations of the Material response to a representative Gaussian pressure field supposed to mimic a single bubble collapse. This gives the size and pressure distribution of the bubble impacts. The prime objective of this study is to find out if the Target Material...

Cavitation erosion: Using the Target Material as a pressure sensor
Journal of Applied Physics, 2015CoAuthors: Samir Chandra Roy, Jeanpierre Franc, Marc C. FivelAbstract:Numerical prediction of mass loss due to cavitation erosion requires the knowledge of the hydrodynamic impact loads generated by cavitation bubble collapses. Experimental measurements of such impact loads using conventional pressure sensors are not reliable (if not impossible) due to the micron size and the very small duration of the loading. In this paper, a new method to estimate these loading conditions is proposed based on cavitation pitting tests and an iterative inverse finite element modeling. The principle of the method is as follows. First, numerous pits corresponding to localized plastically deformed regions are identified from a cavitation test performed in a dedicated tunnel. Then each pit is numerically reproduced by finite element simulations of the Material response to a representative Gaussian pressure field supposed to mimic a single bubble collapse. This gives the size and pressure distribution of the bubble impacts. The prime objective of this study is to find out if the Target Material itself could be used as a pressure sensor or not, i.e., if the cavitation pits left on the surface of the tested specimen could provide the characteristics of the cavitating flow in terms of pressure fields independently of the Target Material. Pitting tests were done on three Materials, namely, 7075 Aluminum alloy (Al7075), 2205 duplex stainless steel (A2205), and NickelAluminum Bronze (NAB) at three different flow conditions and the impact loads have been estimated for each identified pit. Very interestingly, a statistical analysis shows that the estimated impact loads are Material independent at all flow conditions, provided the Material properties are characterized properly. It is also shown that for some Materials, the constitutive parameters obtained from compression tests are not satisfactory.
Marianne Larsen  One of the best experts on this subject based on the ideXlab platform.

protein standardization v value transfer a practical protocol for the assignment of serum protein values from a reference Material to a Target Material
Clinical Chemistry and Laboratory Medicine, 2008CoAuthors: Soren Blirup, Myron A Johnson, Marianne LarsenAbstract:We present a practical protocol for the assignment of values to serum proteins in a Target Material using a Reference Material. This protocol is based on the model of Direct Value Transfer between serum matrices and is intended to improve the value assignment of commercial calibrators using the Reference Material CRM 470 (now labeled ERMDA 470) or similar reference Materials. The procedure describes the general as well as the practical principles involved in the value assignment (with examples). The practical transfer protocol is based on multiple assays of 6 dilutions of the Reference Material and 6 dilutions of the Target Material. The transfer protocol requires several measurements a day repeated on several days, an important prerequisite being that all reconstitutions and dilutions are controlled by weighing thus reducing uncertainty in the transfer. In open systems that allow the use of the Reference Material as calibrator and the Target Material as samples, the proportionality of the two Materials (the presence or absence of matrix effects) can now be directly assessed by evaluating a single regression plot. If no matrix effects are found, the regression line will pass through zero with a slope equal to the ratio of the concentrations of the two Materials. In closed systems, the dedicated commercial calibrator has to be used as such; the Reference Material and the Target Material are now assayed as samples against this calibrator. Two regression plots are therefore obtained; if no matrix effects are present among the two Materials and the calibrator, both the Reference and Target Materials will show zero intercepts, and the ratio of the two slopes will equal the ratio of the concentrations.

protein standardization iv value transfer procedure for the assignment of serum protein values from a reference preparation to a Target Material
Clinical Chemistry and Laboratory Medicine, 2001CoAuthors: Soren Blirupjensen, Myron A Johnson, Marianne LarsenAbstract:A new approach for the assignment of values to serum proteins in a Target Material using a reference preparation has been developed. The procedure describes the general as well as the practical principles involved in the value assignment (with examples). Two models have been developed: 1) The direct value transfer between serum matrices and 2) the indirect value transfer from a pure protein preparation to a serum protein Material. The necessary mathematical equations are developed and explained. The data reduction and statistical evaluation are discussed. The practical procedure (the transfer protocol) is based on six dilutions of the reference preparation assayed together with six dilutions of the Target Material. In this way imprecision is reduced and the proportionality of the two Materials (i.e. the presence or absence of matrix effects) can be assessed directly by evaluating a single regression plot. If no matrix effects are found, the regression line will pass through zero with a slope equal to the ratio of the concentrations of the two Materials. The transfer protocol is based on a multiple point value assignment obtained by several measurements a day repeated on several days, an important prerequisite being that all reconstitutions and dilutions are controlled by weighing.