Turning the current experimental plasma accelerator state-of-the-art from a promising technology into mainstream scientific tools depends critically on high-performance, high-fidelity modeling of complex processes that develop over a wide range of space and time scales. As part of the U.S. Department of Energy's Exascale Computing Project, a team from Lawrence Berkeley National Laboratory, in collaboration with teams from SLAC National Accelerator Laboratory and Lawrence Livermore National Laboratory, is developing a new plasma accelerator simulation tool that will harness the power of future exascale supercomputers for high-performance modeling of plasma accelerators. We present the various components of the codes such as the new Particle-In-Cell Scalable Application Resource (PICSAR) and the redesigned adaptive mesh refinement library AMReX, which are combined with redesigned elements of the Warp code, in the new WarpX software. The code structure, status, early examples of applications and plans are discussed.

No abstract

No abstract

With the recent surge of the use of room-temperature ionic liquids in the syntheses of inorganic nanomaterials, we have successfully integrated the advantages of a thiol-functionalized ionic liquid and the seed growth method to generate palladium nanowires at room temperature. Moreover, the as-prepared palladium nanowires show very high catalytic activity and stability for the Sonogashira coupling reaction.

In this work, we study the near-field radiative heat transfer between two suspended sheets of anisotropic 2D materials. It is found that the radiative heat transfer can be enhanced with orders-of-magnitude over the blackbody limit for nanoscale separation. The enhancement is attributed to the excitation of anisotropic and hyperbolic plasmonic modes. Meanwhile, a large thermal modulation effect, depending on the twisted angle of principal axes between the upper and bottom sheets of anisotropic 2D materials, is revealed. The near-field radiative heat transfer for different concentrations of electron is demonstrated and the role of hyperbolic plasmonic modes is analyzed. Our finding of radiative heat transfer between anisotropic 2D materials may find promising applications in thermal nano-devices, such as non-contact thermal modulators, thermal lithography, thermosphotovoltaics, etc.Thermal radiation is an important physical phenomenon. Any object with temperature T>0K emits electromagnetic (EM) waves due to the fluctuating current generated from thermal motion of charge carriers. According to the Stefan-Boltzmann law, the radiative heat flux between two separated black bodies is given as 2 4 4 4 1 2 3 2 ( ) 60 B bb k S T T c π = −  , where k B is the Boltzmann constant,  is the reduced Planck's constant, c is the speed of light in vacuum, T 1 and T 2 is the high and low temperatures,respectively. For the Stefan-Boltzmann law, the separation distance d is much larger than the thermal wavelength λ th =c/k B T and only the propagation modes are taken into account in the process of radiative heat transfer. However, an additional contribution, i.e., evanescent waves, is dominant and should be considered when the separation distance d is much smaller than λ th (about 10 µm at room temperature). 1-2 The evanescent waves near the surface can be surface plasmon polaritions (SPPs), 3 surface phonon polaritions (SPhPs), 3,4 or even frustrated modes from hyperbolic materials. 5-6 Due to large density of states of evanescent waves, near-field radiative heat transfer (NFRHT) can exceed the blackbody limit by several orders of _____________________________ a) Author to whom correspondence should be addressed. Electronic

No abstract

No abstract

No abstract