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Title: Predictions for Gyro-phase Drift in MDPX

This work assesses the feasibility of observing the gyro-phase drift in the Auburn Magnetized Dusty Plasma Experiment [MDPX, described by Thomas et al., Plasma Phys. Controlled Fusion 54, 124034 (2012)]. The gyro-phase drift arises when a dust grain does not instantaneously reach the in-situ-equilibrium grain charge during gyro-synchronous grain-charge modulation. Koepke et al. [J. Plasma Phys. 79, 1099 (2013)] first suggested using MDPX to observe the gyro-phase drift, and here we use a single-particle trajectory tracker with an iterative velocity solver, using a fixed timestep for grain motion and an adaptive time step for grain charging, to consider all relevant dust grain forces to assess gyro-phase drift arising from gradual inhomogeneity. Additionally, the semi-analytic theory developed by Walker et al. [J. Plasma Phys. 80, 395 (2014)] predicts dust grain motion in abrupt inhomogeneity for MDPX-relevant conditions. We compare three grain-charging models with each other and with the single-particle trajectory tracker and found to predict distinctly different trajectories depending on the treatment of neutral drag and flowing ions. The measurement thresholds for Particle Tracking Velocimetry permit gyro-phase drift detection in MDPX for the abrupt inhomogeneity, given sufficiently large enough UV photoelectron flux (fuv/[nevthe] > 0.01) and low enough neutral gas pressuremore » (less than one mTorr). The Orbit-Motion-Limited charge model and the charge models developed by Patacchini et al. [Phys. Plasmas 14, 062111 (2007)] and Gatti and Kortshagen [Phys. Rev. E 78, 046402 (2008)] can, in principle, be distinguished by gyro-phase drift in the abrupt inhomogeneity, but large magnetic fields, large UV photoelectron flux, and low neutral gas pressure are required. Gyro-phase drift for a gradual inhomogeneity in the ratio ne/ni, arising from the presence of a radial electric field, is predicted to be undetectable.« less
Authors:
ORCiD logo [1] ;  [1] ;  [2]
  1. West Virginia Univ., Morgantown, WV (United States)
  2. Johns Hopkins Univ., Baltimore, MD (United States). Physics Lab.
Publication Date:
Grant/Contract Number:
SC0001939
Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 23; Journal Issue: 10; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Research Org:
West Virginia Univ., Morgantown, WV (United States)
Sponsoring Org:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Maxwell equations; plasma flows; zirconium; plasma diagnostics; plasma sheaths; ultraviolet light; plasma density; trajectory models; electric fields; magnetic fields
OSTI Identifier:
1465172
Alternate Identifier(s):
OSTI ID: 1330400

Walker, J. J., Koepke, M. E., and Zimmerman, M. I.. Predictions for Gyro-phase Drift in MDPX. United States: N. p., Web. doi:10.1063/1.4966202.
Walker, J. J., Koepke, M. E., & Zimmerman, M. I.. Predictions for Gyro-phase Drift in MDPX. United States. doi:10.1063/1.4966202.
Walker, J. J., Koepke, M. E., and Zimmerman, M. I.. 2016. "Predictions for Gyro-phase Drift in MDPX". United States. doi:10.1063/1.4966202. https://www.osti.gov/servlets/purl/1465172.
@article{osti_1465172,
title = {Predictions for Gyro-phase Drift in MDPX},
author = {Walker, J. J. and Koepke, M. E. and Zimmerman, M. I.},
abstractNote = {This work assesses the feasibility of observing the gyro-phase drift in the Auburn Magnetized Dusty Plasma Experiment [MDPX, described by Thomas et al., Plasma Phys. Controlled Fusion 54, 124034 (2012)]. The gyro-phase drift arises when a dust grain does not instantaneously reach the in-situ-equilibrium grain charge during gyro-synchronous grain-charge modulation. Koepke et al. [J. Plasma Phys. 79, 1099 (2013)] first suggested using MDPX to observe the gyro-phase drift, and here we use a single-particle trajectory tracker with an iterative velocity solver, using a fixed timestep for grain motion and an adaptive time step for grain charging, to consider all relevant dust grain forces to assess gyro-phase drift arising from gradual inhomogeneity. Additionally, the semi-analytic theory developed by Walker et al. [J. Plasma Phys. 80, 395 (2014)] predicts dust grain motion in abrupt inhomogeneity for MDPX-relevant conditions. We compare three grain-charging models with each other and with the single-particle trajectory tracker and found to predict distinctly different trajectories depending on the treatment of neutral drag and flowing ions. The measurement thresholds for Particle Tracking Velocimetry permit gyro-phase drift detection in MDPX for the abrupt inhomogeneity, given sufficiently large enough UV photoelectron flux (fuv/[nevthe] > 0.01) and low enough neutral gas pressure (less than one mTorr). The Orbit-Motion-Limited charge model and the charge models developed by Patacchini et al. [Phys. Plasmas 14, 062111 (2007)] and Gatti and Kortshagen [Phys. Rev. E 78, 046402 (2008)] can, in principle, be distinguished by gyro-phase drift in the abrupt inhomogeneity, but large magnetic fields, large UV photoelectron flux, and low neutral gas pressure are required. Gyro-phase drift for a gradual inhomogeneity in the ratio ne/ni, arising from the presence of a radial electric field, is predicted to be undetectable.},
doi = {10.1063/1.4966202},
journal = {Physics of Plasmas},
number = 10,
volume = 23,
place = {United States},
year = {2016},
month = {10}
}