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SUMMARY:Interplay between particle transport\, zonal flows and zonal densi
ty in Dissipative Trapped-Electron Mode turbulence
DTSTART;VALUE=DATE-TIME:20210514T101000Z
DTEND;VALUE=DATE-TIME:20210514T103000Z
DTSTAMP;VALUE=DATE-TIME:20211027T105331Z
UID:indico-contribution-17627@conferences.iaea.org
DESCRIPTION:Speakers: MICHAEL LECONTE (NFRI)\nThe H-Mode is the main regim
e of operation for present and future fusion devices like ITER. The transi
tion from L-mode to H-mode (LH transition) has been studied for more than
20 years [1]. One important aspect of the LH transition is the abrupt supp
ression of the turbulent particle transport at the plasma edge [2]. Turbu
lence driven flows\, i.e. zonal flows are believed to play a major role in
the transition by providing the initial quench of turbulence [3]. Analyti
cal models of zonal flow nonlinear generation can be classified into two c
ategories: the parametric interaction approach [4]\, and the wave-kinetic
approach [5]. Recently\, Ref. [6] proposed a new quantum-mechanical-like f
ramework to systematically derive the wave-kinetic equation (WKE) from the
drift-wave model with adiabatic electrons\, i.e. from the Charney-Hasegaw
a-Mima equation [7]\, and also to account for dissipation and/or growth. I
n this work\, we extend the wave-kinetic equation to account for non-adiab
atic electrons. Starting from the Dissipative-trapped-electron mode (DTEM)
fluid model [8\,9]\, a basic representative model for edge turbulence des
cribing a collisional drift-wave instability due to trapped electrons\, we
apply the wave-kinetic formalism of Ref. [6]. We include both the zonal f
lows and the zonal density\, i.e. the time-dependent corrugation of the de
nsity profile. In previous work [9]\, we showed using the parametric forma
lism that zonal flows can affect the transport crossphase between density
and potential fluctuations. Here\, we consider a similar mechanism: using
the wave-kinetic formalism\, we show that the transport crossphase is modu
lated by zonal density corrugations. In turn\, this modulation nonlinearly
drives the zonal density corrugations. This is the analog of ETG growth-r
ate modulation by ion-scale turbulence [10]\, altough here\, we find that
the effect is always stabilizing. In turn\, this modulation nonlinearly dr
ives the zonal density corrugations.\nThe extended predator-prey model is
derived for the turbulence energy ε\, zonal flow energy $U^2 =\\int V_{\\
rm zon}^2 dr$ and zonal density energy $N^2 = \\int n_{\\rm zon}^2 dr$:\n\
n$\n\\frac{d\\epsilon}{dt} = \\gamma \\epsilon - a_1 \\epsilon U^2 - a_2 \
\epsilon N^2 - \\gamma_{NL} \\epsilon^2\,\n$\n\n$\n \\frac{d U^2}{dt} = b_
1 \\epsilon U^2 - \\mu U^2\,\n$\n\n$\n\\frac{d N^2}{dt} = c_1 \\epsilon N^
2 - c_2 N^2\,\n$\n\nHere\, the terms $a_1$ and $b_1$ represent nonlinear
coupling between drift-waves and zonal flows\, while the terms $a_2$ and $
c_1$ represent nonlinear coupling between drift-waves and zonal density. Z
onal flow damping occurs via neoclassical friction (μ). The coefficient
s $a_2$ and $c_1$ associated to zonal density dynamics are proportional
to the inverse of the de-trapping rate ν\, i.e. inversely proportional t
o electron-ion collision frequency.\nFor different values of the de-trappi
ng rate\, the predator-prey model exhibits different saturation mechanisms
. In particular\, for ν=1\, the system shows a saturate state dominated b
y zonal density\, while for larger values of ν\, zonal flows are dominan
t and zonal density is subdominant.\n\n[1] Y. Zhou\, H. Zhu and I. Dodin\,
Plasma Phys. Control. Fusion 61\, 075003 (2019).\n[2] G.R. Tynan\, A. Fuj
isawa and G. McKee\, Plasma Phys. Control. Fusion 51\, 113001 (2009).\n[3]
P.H. Diamond\, A. Hasegawa and K. Mima\, Plasma Phys. Control. Fusion 53
\, 124001 (2011).\n[4] L. Chen\, Z. Lin and R. White\, Phys. Plasmas 8\, 3
129 (2000).\n[5] N. Mattor and P.H. Diamond\, Phys. Plasmas 1\, 4002 (1994
)\, A.I. Smolyakov and P.H. Diamond\, Phys. Plasmas 6\, 4410 (1999).\n[6]
Y. Zhou\, H. Zhu and I. Dodin\, Plasma Phys. Control. Fusion 61\, 075003 (
2019).\n[7] A. Hasegawa and K. Mima\, Phys. Fluids 21\, 87 (1978).\n[8] D.
A. Baver\, P.W. Terry\, R. Gatto and E. Fernandez\, Phys. Plasmas 9\, 3318
(2002).\n[9] M. Leconte and R. Singh\, Plasma Phys. Controlled Fusion 42\
, R35 (2005).\n[10] C. Holland and P.H. Diamond\, Phys. Plasmas 11\, 1043
(2004).\n\nhttps://conferences.iaea.org/event/214/contributions/17627/
LOCATION:Virtual Event
URL:https://conferences.iaea.org/event/214/contributions/17627/
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