skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Vortex circulation patterns in planar microdisk arrays

Authors:
 [1];  [2]; ORCiD logo [3];  [4];  [5];  [3];  [6];  [7];  [8];  [4]
  1. Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA, Institut für Nanostruktur- und Festkörperphysik, Universität Hamburg, Jungiusstrasse 11, 20355 Hamburg, Germany
  2. Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
  3. Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
  4. Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA, Physics Department, University of California, 1156 High Street, Santa Cruz, California 95064, USA
  5. Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA, Department of Emerging Materials Science, Daegu Gyeongbuk Institute of Science and Technology, Daegu 711-873, South Korea
  6. Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
  7. Institut für Nanostruktur- und Festkörperphysik, Universität Hamburg, Jungiusstrasse 11, 20355 Hamburg, Germany
  8. Max-Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761 Hamburg, Germany
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1371495
Grant/Contract Number:
AC02-05- CH11231; AC02-05-CH11231
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 110; Journal Issue: 26; Related Information: CHORUS Timestamp: 2018-02-14 12:22:09; Journal ID: ISSN 0003-6951
Publisher:
American Institute of Physics
Country of Publication:
United States
Language:
English

Citation Formats

Velten, Sven, Streubel, Robert, Farhan, Alan, Kent, Noah, Im, Mi-Young, Scholl, Andreas, Dhuey, Scott, Behncke, Carolin, Meier, Guido, and Fischer, Peter. Vortex circulation patterns in planar microdisk arrays. United States: N. p., 2017. Web. doi:10.1063/1.4990990.
Velten, Sven, Streubel, Robert, Farhan, Alan, Kent, Noah, Im, Mi-Young, Scholl, Andreas, Dhuey, Scott, Behncke, Carolin, Meier, Guido, & Fischer, Peter. Vortex circulation patterns in planar microdisk arrays. United States. doi:10.1063/1.4990990.
Velten, Sven, Streubel, Robert, Farhan, Alan, Kent, Noah, Im, Mi-Young, Scholl, Andreas, Dhuey, Scott, Behncke, Carolin, Meier, Guido, and Fischer, Peter. Mon . "Vortex circulation patterns in planar microdisk arrays". United States. doi:10.1063/1.4990990.
@article{osti_1371495,
title = {Vortex circulation patterns in planar microdisk arrays},
author = {Velten, Sven and Streubel, Robert and Farhan, Alan and Kent, Noah and Im, Mi-Young and Scholl, Andreas and Dhuey, Scott and Behncke, Carolin and Meier, Guido and Fischer, Peter},
abstractNote = {},
doi = {10.1063/1.4990990},
journal = {Applied Physics Letters},
number = 26,
volume = 110,
place = {United States},
year = {Mon Jun 26 00:00:00 EDT 2017},
month = {Mon Jun 26 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on June 30, 2018
Publisher's Accepted Manuscript

Citation Metrics:
Cited by: 2works
Citation information provided by
Web of Science

Save / Share:
  • For this work, we studied curvature-driven modifications to the magnetostatic coupling of vortex circulation and polarity in soft-magnetic closely packed cap arrays. A phase diagram for the magnetic remanent/transition states at room temperature as a function of diameter and thickness was assembled. For specimens with vortex remanent state (40 nm-thick Permalloy on 330 nm spherical nanoparticles), both vortex circulation and polarity were visualized. Intercap coupling upon vortex nucleation leads to the formation of vortex circulation patterns in closely packed arrays. The remanent circulation pattern can be tailored choosing the direction of the applied magnetic field with respect to the symmetrymore » axis of the hexagonal array. An even and random distribution of vortex polarity indicates the absence of any circulation-polarity coupling.« less
  • We present a simple silicon based microfabrication process that produces an array of SiO2 microdisks using UV lithography. High-resolution SEM images of these structures indicate a smooth outer microdisk cavity surface. Photoemission measurements were performed at different spots on the microdisk and compared with measurements inside the cavity. A silicon to oxygen atomic concentration ratio of 1:2 obtained during depth profiling confirms that the entire microdisk is made up of stoichometric SiO2. In contrast, the inner cavity is mostly silicon with native oxide on top. We discuss the usefulness of SiO2 microdisks in optics for light trapping experiments.
  • This article reports on the joint success of two independent lines of research, each of them being a multi-year international effort. One of these is the development of innovative sources, such as planar wire arrays (PWAs). PWAs turned out to be a prolific radiator, which act mainly as a resistor, even though the physical mechanism of efficient magnetic energy conversion into radiation still remains unclear. We review the results of our extensive studies of PWAs. We also report the new results of the experimental comparison PWAs with planar foil liners (another promising alternative to wire array loads at multi-mega-ampere generators).more » Pioneered at UNR, the PWA Z-pinch loads have later been tested at the Sandia National Laboratories (SNL) on the Saturn generator, on GIT-12 machine in Russia, and on the QiangGuang-1 generator in China, always successfully. Another of these is the drastic improvement in energy efficiency of pulsed-power systems, which started in early 1980s with Zucker's experiments at Naval Research Laboratory (NRL). Successful continuation of this approach was the Load Current Multiplier (LCM) proposed by Chuvatin in collaboration with Rudakov and Weber from NRL. The 100 ns LCM was integrated into the Zebra generator, which almost doubled the plasma load current, from 0.9 to 1.7 MA. The two above-mentioned innovative approaches were used in combination to produce a new compact hohlraum radiation source for ICF, as jointly proposed by SNL and UNR [Jones et al., Phys. Rev. Lett. 104, 125001 (2010)]. The first successful proof-of-the-principle experimental implementation of new hohlraum concept at university-scale generator Zebra/LCM is demonstrated. A numerical simulation capability with VisRaD code (from PRISM Co.) established at UNR allowed for the study of hohlraum coupling physics and provides the possibility of optimization of a new hohlraum. Future studies are discussed.« less
  • Nitrous oxide (N2O) measured on board the ER-2 aircraft during the Airborne Arctic Stratospheric Expedition 2 (AASE 2) has been used to monitor descent of air inside the Arctic vortex between October 1991 and March 1992. Monthly mean N2O fields are calculated from the flight data and then compared with mean fields calculated from the high-resolution Geophysical Fluid Dynamics Laboratory general circulation model SKYHI in order to evaluate the model`s simulation of the polar vortex. From late fall through winter the model vortex evolves in much the same way as the 1991-1992 vortex, with N2O gradients at the edge becomingmore » progressively steeper. The October to March trends in N2O profiles inside the vortex are used to verify daily net heating rates in the vortex that were computed from clear sky radiative heating rates and National Meteorological Center temperature observations. The computed heating rates successfully estimate the descent of vortex air from December through February but suggest that before December, air at high latitudes may not be isolated from the midlatitudes. SKYHI heating rates are in good agreement with the computed rates but tend to be slightly higher (i.e., less cooling) due to meteorological differences between SKYHI and the 1991-1992 winter. Three ER-2 flights measured N2O just north of the subtropical jet. These low-midlatitude profiles show only slight differences from the high-midlatitude profiles (45 deg - 60 deg N), indicating strong meridional mixing in the midlatitude `surf zone.` Mean midwinter N2O profiles inside and outside the vortex calculated from AASE 2 data are shown to be nearly identical to 1989 AASE profiles, pointing to the N2O/potential temperature relationship as an excellent marker for vortex air.« less
  • The relationship between turbomachinery blade circulation and tip clearance vortex circulation measured experimentally is examined using three-dimensional viscous flow computations. It is shown that the clearance vortex circulation one would measure is dependent on the placement of the fluid contour around which the circulation measurement is taken. Radial transport of vorticity results in the magnitude of the measured clearance vortex circulation generally being less than the blade circulation. For compressors, radial transport of vorticity shed form the blade tip in proximity to the endwall is the principal contributor to the discrepancy between the measured vortex circulation and blade circulation. Further,more » diffusion of vorticity shed at the blade tip toward the endwall makes it impossible in most practical case to construct a fluid contour around the vortex that encloses all, and only, the vorticity shed from the blade tip. One should thus not expect agreement between measured tip clearance vortex circulation and circulation around the blade.« less