Fabrication of large-area uniform carbon nanotube foams as near-critical-density targets for laser–plasma experiments

Carbon nanotube foams (CNFs) have been successfully used as near-critical-density targets in the laser-driven acceleration of high-energy ions and electrons. Here we report the recent advances in the fabrication technique of such targets. With the further developed floating catalyst chemical vapor deposition (FCCVD) method, large-area ( $>25\kern0.5em {\mathrm{cm}}^2$ ) and highly uniform CNFs are successfully deposited on nanometer-thin metal or plastic foils as double-layer targets. The density and thickness of the CNF can be controlled in the range of $1{-}13\kern0.5em \mathrm{mg}/{\mathrm{cm}}^3$ and $10{-}200\kern0.5em \mu \mathrm{m}$ , respectively, by varying the synthesis parameters. The dependence of the target properties on the synthesis parameters and the details of the target characterization methods are presented for the first time.

Target Characterization and Scattering Power Decomposition for Full and Compact Polarimetric SAR Data

This manuscript was accepted for publication on IEEE Transactions on Geoscience and Remote Sensing.<br><br>Abstract: In radar polarimetry, incoherent target decomposition<br>techniques help extract scattering information from polarimetric<br>SAR data. This is achieved either by fitting appropriate scattering models or by optimizing the received wave intensity<br>through the diagonalization of the coherency (or covariance)<br>matrix. As such, the received wave information depends on<br>the received antenna configuration. Additionally, a polarimetric<br>descriptor that is independent of the received antenna configuration might provide additional information which is missed by the individual elements of the coherency matrix. This implies that existing target characterization techniques might neglect this information. In this regard, we suitably utilize the 2D and 3D Barakat degree of polarization which is independent of the received antenna configuration to obtain distinct polarimetric information for target characterization. In this study, we introduce new roll-invariant scattering-type parameters for both full-polarimetric (FP) and compact-polarimetric (CP) SAR data. These new parameters jointly use the information of the 2D and 3D Barakat degree of polarization and the elements of the coherency (or covariance) matrix. We use these new scattering type parameters, which provide equivalent information as the Cloude alpha for FP SAR data and the ellipticity parameter chi for CP SAR data, to characterize various targets adequately. Additionally, we appropriately utilize these new scattering-type parameters to obtain unique non-model based three-component scattering power decomposition techniques. We obtain the even-bounce, and the odd-bounce scattering powers by modulating the total polarized power by a proper geometrical factor derived using the new scattering-type parameters for FP and CP SAR data. The diffused scattering power is obtained as the depolarized fraction of the total power. Moreover, due to the nature of its formulation, the decomposition scattering powers are nonnegative and roll-invariant while the total power is conserved. The proposed method is both qualitatively and quantitatively assessed utilizing the L-band ALOS-2 and C-band Radarsat-2 FP and the associated simulated CP SAR data.