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

Title: A basic plasma test for gyrokinetics: GDC turbulence in LAPD

; ; ORCiD logo; ; ;
Publication Date:
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
OSTI Identifier:
Grant/Contract Number:
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Plasma Physics and Controlled Fusion
Additional Journal Information:
Journal Volume: 59; Journal Issue: 2; Related Information: CHORUS Timestamp: 2017-01-17 04:16:03; Journal ID: ISSN 0741-3335
IOP Publishing
Country of Publication:
United Kingdom

Citation Formats

Pueschel, M. J., Rossi, G., Told, D., Terry, P. W., Jenko, F., and Carter, T. A. A basic plasma test for gyrokinetics: GDC turbulence in LAPD. United Kingdom: N. p., 2017. Web. doi:10.1088/1361-6587/aa52e6.
Pueschel, M. J., Rossi, G., Told, D., Terry, P. W., Jenko, F., & Carter, T. A. A basic plasma test for gyrokinetics: GDC turbulence in LAPD. United Kingdom. doi:10.1088/1361-6587/aa52e6.
Pueschel, M. J., Rossi, G., Told, D., Terry, P. W., Jenko, F., and Carter, T. A. Tue . "A basic plasma test for gyrokinetics: GDC turbulence in LAPD". United Kingdom. doi:10.1088/1361-6587/aa52e6.
title = {A basic plasma test for gyrokinetics: GDC turbulence in LAPD},
author = {Pueschel, M. J. and Rossi, G. and Told, D. and Terry, P. W. and Jenko, F. and Carter, T. A.},
abstractNote = {},
doi = {10.1088/1361-6587/aa52e6},
journal = {Plasma Physics and Controlled Fusion},
number = 2,
volume = 59,
place = {United Kingdom},
year = {Tue Jan 17 00:00:00 EST 2017},
month = {Tue Jan 17 00:00:00 EST 2017}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1088/1361-6587/aa52e6

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

Save / Share:
  • Strongly intermittent turbulence is observed in the shadow of a limiter in the Large Plasma Device (LAPD) and in both the inboard and outboard scrape-off-layer (SOL) in the Electric Tokamak (ET) at UCLA. In LAPD, the amplitude probability distribution function (PDF) of the turbulence is strongly skewed, with density depletion events (or ''holes'') dominant in the high density region and density enhancement events (or ''blobs'') dominant in the low density region. Two-dimensional cross-conditional averaging shows that the blobs are detached, outward-propagating filamentary structures with a clear dipolar potential while the holes appear to be part of a more extended turbulentmore » structure. A statistical study of the blobs reveals a typical size of ten times the ion sound gyroradius and a typical velocity of one tenth the sound speed. In ET, intermittent turbulence is observed on both the inboard and outboard midplane.« less
  • Energy dynamics calculations in a 3D fluid simulation of drift wave turbulence in the linear Large Plasma Device [W. Gekelman et al., Rev. Sci. Instrum. 62, 2875 (1991)] illuminate processes that drive and dissipate the turbulence. These calculations reveal that a nonlinear instability dominates the injection of energy into the turbulence by overtaking the linear drift wave instability that dominates when fluctuations about the equilibrium are small. The nonlinear instability drives flute-like (k{sub Parallel-To }=0) density fluctuations using free energy from the background density gradient. Through nonlinear axial wavenumber transfer to k{sub Parallel-To }{ne}0 fluctuations, the nonlinear instability accesses themore » adiabatic response, which provides the requisite energy transfer channel from density to potential fluctuations as well as the phase shift that causes instability. The turbulence characteristics in the simulations agree remarkably well with experiment. When the nonlinear instability is artificially removed from the system through suppressing k{sub Parallel-To }=0 modes, the turbulence develops a coherent frequency spectrum which is inconsistent with experimental data. This indicates the importance of the nonlinear instability in producing experimentally consistent turbulence.« less
  • This work presents demonstrative test results of CMSB by simulated helium glow discharge exhaust gas condition in 60 l/min of flow rate. This work focused on H{sub 2} and HT adsorption and regeneration performance of CMSB and optimum regeneration procedure, so that the operation cycle time becomes smaller. Test results showed consistency with bench-scale experiments. Obtained engineering data are applicable for the design of the CMSB process for ITER He GDC gas cleanup. As the results of this work, it was demonstrated that CMSB process could clean up 54.3 SLM of He stream with H{sub 2}(400) ppm+HT(0.5 ppm). Regeneration performancemore » in various total pressure were obtained and evaluated by the calculation and clarified necessary information for determining the optimum regeneration procedure of CMSB which allow continuous operation in the shorter period of operation cycle (adsorption and regeneration). 6 refs., 5 figs., 1 tab.« less
  • The self-consistency of the renormalized perturbation theory of Zhang and Mahajan (Phys. Rev. 132, 1759 (1985)) is demonstrated by applying it to the Vlasov--Poisson system and showing that the theory has the correct weak turbulence limit. Energy conservation is proved to arbitrary high order for the electrostatic drift waves. The theory is applied to derive renormalized equations for a low-beta gyrokinetic system. Comparison of this theory with other current theories is presented.
  • In magnetized plasmas, a turbulent cascade occurs in phase space at scales smaller than the thermal Larmor radius ('sub-Larmor scales') [Tatsuno et al., Phys. Rev. Lett. 103, 015003 (2009)]. When the turbulence is restricted to two spatial dimensions perpendicular to the background magnetic field, two independent cascades may take place simultaneously because of the presence of two collisionless invariants. In the present work, freely decaying turbulence of two-dimensional electrostatic gyrokinetics is investigated by means of phenomenological theory and direct numerical simulations. A dual cascade (forward and inverse cascades) is observed in velocity space as well as in position space, whichmore » we diagnose by means of nonlinear transfer functions for the collisionless invariants. We find that the turbulence tends to a time-asymptotic state, dominated by a single scale that grows in time. A theory of this asymptotic state is derived in the form of decay laws. Each case that we study falls into one of three regimes (weakly collisional, marginal, and strongly collisional), determined by a dimensionless number D{sub *}, a quantity analogous to the Reynolds number. The marginal state is marked by a critical number D{sub *}=D{sub 0} that is preserved in time. Turbulence initialized above this value become increasingly inertial in time, evolving toward larger and larger D{sub *}; turbulence initialized below D{sub 0} become more and more collisional, decaying to progressively smaller D{sub *}.« less