Collisionless absorption in sharp-edged plasmas

Role of surface roughness in hard-x-ray emission from femtosecond-laser-produced copper plasmas

“…Our laser pulses have an insignificant prepulse component and the measurements of Doppler shift from plasma expansion have indicated [27] that the ratio xosc L is about 1 and L λ is about 0.01. For these parameters, simulations [28] show that VH could give a T hot of about 30 keV, under similar conditions, which is quite close to the measured value of the higher temperature component (reflectivity studies are done which support the existence of VH under our conditions).…”

“…The exponential fit for the p-polarization data gives a temperature of 15 ± 3 keV . This temperature component is again on par with the value obtained from simulations for the parameters valid at this intensity [28]. No fit is attempted on the data obtained using s-polarized light as the counts beyond 50 keV are too few to get a good fit.…”

Hot electron and x-ray production from intense laser irradiation of wavelength-scale polystyrene spheres

“…pulses at this intensity our interaction qualitatively corresponds to vacuum heating as modeled by Gibbon et al 25 This indicated that plasma expansion of well under the electron oscillation amplitude ͑ osc ϳ 15 nm͒ occurred and that our pulses would interact with well defined spheres that have not undergone significant expansion prior to the arrival of the peak of the pulse. Furthermore, we simulated the expansion of a spherical plasma using the Medusa 103 Lagrangian hydrodynamic code and confirmed that we expected very little expansion of these small spheres.…”

“…To determine the temperature of hot electrons generated we fit an electron energy distribution to the data using the methodology described by McCall et al 27 Because we examine hard x-rays being emitted from a thin target, we can assume there is an exponential distribution of the bremsstrahlung x-ray radiation and that the x-ray temperature and the hot-electron temperature are equivalent. 25 The x-ray spectrum is then convolved with the detector response and filter transmission functions. We then found the hot-electron temperature which minimized the error in fit between the data and the implied exponential x-ray spectrum.…”

Investigations of Field Dynamics in Laser Plasmas with Proton Imaging

“…Also a finite density profile should be considered for a more realistic case. In reference [52] simulations for different plasma scale length were done showing an absorption of the laser energy about 70 % at low intensities (Iλ 2 = 10 16 W/cm 2 µm 2 ) and scale lengths of L/λ ∼ 0.1. At high intensities and short scale lengths the absorption is only about 10 − 15 %.…”