Bulletin of the American Physical Society
2018 Annual Meeting of the APS Four Corners Section
Volume 63, Number 16
Friday–Saturday, October 12–13, 2018; University of Utah, Salt Lake City, Utah
Session J05: AMO3: Ultraviolet and Plasmas |
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Chair: Chen Yen Lai, Los Alamos National Laboratory Room: CSC 208 |
Saturday, October 13, 2018 8:00AM - 8:24AM |
J05.00001: High resolution holography with table top extreme ultraviolet lasers Invited Speaker: Mario C Marconi The development of tabletop extreme ultraviolet (EUV) lasers enabled the implementation of several experimental techniques like high-resolution imaging, nanolithography, mass spectroscopy, etc. in a small laboratory size environment. In this talk I will summarize results of high-resolution holographic imaging using a tabletop EUV laser. The approach we used was Fourier transform holography (FTH). FTH has the distinctive advantage that the image reconstruction process is straightforward. It can be numerically reconstructed by calculating the inverse Fourier transform of the interference pattern collected on the charge coupled device detector. The point reference source in FTH is typically obtained using a small pinhole located in the object plane. This usually limits the object size in order to match the amount of light to the intensity of the reference pinhole. In our experiments we utilized a setup in which this limitation was mitigated using a reference point source created with a Fresnel zone plate that split the laser beam to generate the illumination and reference waves. The pulsed illumination is generated by a tabletop EUV laser at 46.9nm wavelength, (750μm coherence length and 550μm coherence radius). Multiple shots and single shot holograms were acquired. A resolution of 128±33 nm was obtained for multiple shots holograms (accumulation of 20 shots). For single shot exposures, due to the lower signal-to-noise level the resolution was reduced to 159±58 nm. Three-dimensional imaging was also achieved by numerical refocusing the reconstructed image. A sequence of single shot holograms allowed for the composition of holographic movies of nano-scale oscillating cantilevers at megahertz frequencies. Also, holograms obtained at 13.9nm will be presented, in which we obtained a spatial resolution below 100nm. |
Saturday, October 13, 2018 8:24AM - 8:36AM |
J05.00002: Employing an Aluminum Fluoride Thin Film Interference layer to find Optical Constants in the Extreme Ultraviolet J Gabriel Richardson, David D Allred, Jacob Siebach, Kylie Wolfe, Maximiliano Barona, R Steven Turley Interference fringes in reflectance and transmission are invaluable in obtaining thicknesses and optical constants of thin-films. However, interference fringes may not be produced for absorbing materials. A technique to deal with this, in the visible is to place a transparent layer beneath the absorbing thin-film (Hilfiker, et al.) A portion of the light passing through that semitransparent film, reflecting off the substrate and after transmitting again through the film, interferes with the front-surface, reflected light producing interference fringes whose position depends on the layers’ thicknesses and indices, and the light’s wavelength and angle of incidence. The damping of the fringes highly constrains the optical constants of this overlayer. We have extended this approach into the extreme ultraviolet to obtain the optical constants of aluminum fluoride between 17.1 and 49.5 nm using evaporated aluminum as a “semitransparent” interference layer. The AlF3 is evaporated within minutes after the aluminum and without breaking vacuum so as to minimize the presence of oxygen on the Al film. The AlF3 also acts as a barrier layer, drastically retarding the oxidation of the aluminum film after it is removed from the deposition system. |
Saturday, October 13, 2018 8:36AM - 8:48AM |
J05.00003: Ion friction at small values of the Coulomb logarithm Robert Tucker Sprenkle, Ross L Spencer, Scott Douglas Bergeson We create a dual-species ultracold neutral plasma (UNP) by photo-ionizing Yb and Ca atoms in a dual-species magneto-optical trap. Unlike single-species UNP expansion, these plasmas are well outside of the collisionless (Vlasov) approximation. We observe the mutual interaction of the Yb and Ca ions by measuring the velocity distribution for each ion species separately. We model the expansion using a fluid code including ion-ion friction and compare with experimental results to obtain a value of the Coulomb logarithm of 0.04 |
Saturday, October 13, 2018 8:48AM - 9:00AM |
J05.00004: Hydrodynamic modes in magnetized chiral plasma with vorticity Denys Rybalka, Eduard V Gorbar, Igor A Shovkovy Many physical systems can be viewed as plasmas made of chiral particles. Examples include the quark-gluon plasma produced in the heavy-ion collisions, electron fluids of Weyl semimetals, lepton and quark matter in compact stars, supernovas and the early Universe. Hydrodynamics is a powerful tool for describing a long-wavelength behavior of such systems when the first-principles quantum field theory calculations become impractical. In this talk I will briefly review the phenomenology of chiral plasmas and lay a roadmap for deriving the hydrodynamical equations from the chiral kinetic theory and underlying quantum field theory. Then I will present the equilibrium state and collective modes in a rotating chiral plasma subjected to an external magnetic field. Lastly, I will argue the necessity of dynamical treatment of electromagnetic and plasma parameters and discuss further problems. |
Saturday, October 13, 2018 9:00AM - 9:12AM |
J05.00005: 3D Printing Motorized Mirror Mounts Dallen Petersen, Jarom S. Jackson, Nick Porter, Dallin S. Durfee We are working on using an interferometer to image objects from a distance. This requires high precision mirror control to properly direct the lasers. After exploring commercial options, we decided to create our own motorized mirror controllers using 3D printed parts and basic stepper motors. We are currently working on characterizing our preliminary model to see how well it works, after which, we plan to make improvements and compare the performance. |
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