21 research outputs found
Interaction between electrostatic collisionless shocks generates strong magnetic fields
The head-on collision between electrostatic shocks is studied via multi-dimensional particle-in-cell simulations. A strong magnetic field develops after the interaction, which causes the shock velocities to drop significantly. This transverse magnetic field is generated by the Weibel instability, which is driven by pressure anisotropies due to longitudinal electron heating while the shocks approach each other. The possibility to explore the physics underpinning the shock collision in the laboratory with current laser facilities is discussed.info:eu-repo/semantics/publishedVersio
The Debye-Waller Factor in solid 3He and 4He
The Debye-Waller factor and the mean-squared displacement from lattice sites
for solid 3He and 4He were calculated with Path Integral Monte Carlo at
temperatures between 5 K and 35 K, and densities between 38 nm^(-3) and 67
nm^(-3). It was found that the mean-squared displacement exhibits finite-size
scaling consistent with a crossover between the quantum and classical limits of
N^(-2/3) and N^(-1/3), respectively. The temperature dependence appears to be
T^3, different than expected from harmonic theory. An anisotropic k^4 term was
also observed in the Debye-Waller factor, indicating the presence of
non-Gaussian corrections to the density distribution around lattice sites. Our
results, extrapolated to the thermodynamic limit, agree well with recent values
from scattering experiments.Comment: 5 figure