We demonstrated the interaction of a gold cone target with a femto second(fs) laser pulse above the relativistic intensity of 1.37×10 18 μm 2 W/cm 2.Relativistic electrons with energy above 2 MeV were observed.A 25%-40% increase of the electron temperature is achieved compared to the case when a plane gold target is used.The electron temperature increase results from the guiding of the laser beam at the tip and the intense quasistatic magnetic field in the cone geometry.The behavior of the relativistic electrons is verified in our 2D-PIC simulations.
A Princeton Instruments PI-LCX 1300 charge-coupled device(CCD) camera used for X-ray spectrum measurements in laser-plasma experiments is calibrated using three radioactive sources and investigated with the Monte Carlo code Geant4. The exposure level is controlled to make the CCD work in single photon counting mode. A summation algorithm for obtaining accurate X-ray spectra is developed to reconstruct the X-ray spectra, and the results show that the developed algorithm efectively reduces the low-energy tail caused by split pixel events. The obtained CCD energy response shows good linearity. The detection eficiency curves from both Monte Carlo simulations and the manufacturer agree well with the experimental results. This consistency demonstrates that event losses in charge collection processes are negligible when the developed summation algorithm of split pixel events is employed.
High-order interpolation algorithms for charge conservation in Particle-inCell(PIC)simulations are presented.The methods are valid for the case that a particle trajectory is a zigzag line.The second-order and third-order algorithms which can be applied to any even-order and odd-order are discussed in this paper,respectively.Several test simulations are performed to demonstrate their validity in two-dimensional PIC code.Compared with the simulation results of one-order,high-order algorithms have advantages in computation precision and enlarging the grid scales which reduces the CPU time.
