116 citations · 548 across the 16 of their papers we have counts for
16 papers
Saturation of magnetised plasma turbulence by propagating zonal flows
Richard Nies, Felix Parra, Michael Barnes +2
Strongly driven ion-scale turbulence in tokamak plasmas is shown to be regulated by a new propagating zonal flow mode, the toroidal secondary mode, which is nonlinearly supported b…
New linear stability parameter to describe low- electromagnetic microinstabilities driven by passing electrons in axisymmetric toroidal geometry
M. R. Hardman, F. I. Parra, B. S. Patel +8
In magnetic confinement fusion devices, the ratio of the plasma pressure to the magnetic field energy, , can become sufficiently large that electromagnetic microinstabilities be…
A phase-shift-periodic parallel boundary condition for low-magnetic-shear scenarios
D. A. St-Onge, M. Barnes, F. I. Parra
We formulate a generalized periodic boundary condition as a limit of the standard twist-and-shift parallel boundary condition that is suitable for simulations of plasmas with low m…
A novel approach to radially global gyrokinetic simulation using the flux-tube code
D. A. St-Onge, M. Barnes, F. I. Parra
A novel approach to global gyrokinetic simulation is implemented in the flux-tube code . This is done by using a subsidiary expansion of the gyrokinetic equation i…
Zonally dominated dynamics and Dimits threshold in curvature-driven ITG turbulence
P. G. Ivanov, A. A. Schekochihin, W. Dorland +2
The saturated state of turbulence driven by the ion-temperature-gradient instability is investigated using a two-dimensional long-wavelength fluid model that describes the perturbe…
A Scale-Separated Approach for Studying Coupled Ion and Electron Scale Turbulence
M. R. Hardman, M. Barnes, C. M. Roach +1
Multiple space and time scales arise in plasma turbulence in magnetic confinement fusion devices because of the smallness of the square root of the electron-to-ion mass ratio $(m_e…
Ion-scale turbulence in MAST: anomalous transport, subcritical transitions, and comparison to BES measurements
F. van Wyk, E. G. Highcock, A. R. Field +4
We investigate the effect of varying the ion temperature gradient (ITG) and toroidal equilibrium scale sheared flow on ion-scale turbulence in the outer core of MAST by means of lo…
Symmetry breaking in MAST plasma turbulence due to toroidal flow shear
M. F. J. Fox, F. van Wyk, A. R. Field +3
The flow shear associated with the differential toroidal rotation of tokamak plasmas breaks an underlying symmetry of the turbulent fluctuations imposed by the up-down symmetry of…
Observation of oscillatory radial electric field relaxation in a helical plasma
J. A. Alonso, E. Sanchez, I. Calvo +13
Measurements of the relaxation of a zonal electrostatic potential perturbation in a non-axisymmetric magnetically confined plasma are presented. A sudden perturbation of the plasma…
Dependence of intrinsic rotation reversals on collisionality in MAST
J. C. Hillesheim, F. I. Parra, M. Barnes +6
Tokamak plasmas rotate even without external injection of momentum. A Doppler backscattering system installed at MAST has allowed this intrinsic rotation to be studied in Ohmic L-m…
Intrinsic momentum transport in up-down asymmetric tokamaks
Justin Ball, Felix I. Parra, Michael Barnes +4
Recent work demonstrated that breaking the up-down symmetry of tokamak flux surfaces removes a constraint that limits intrinsic momentum transport, and hence toroidal rotation, to…
Zero-Turbulence Manifold in a Toroidal Plasma
E. G. Highcock, A. A. Schekochihin, S. C. Cowley +4
Sheared toroidal flows can cause bifurcations to zero-turbulent-transport states in tokamak plasmas. The maximum temperature gradients that can be reached are limited by subcritica…
Transport Bifurcation Induced by Sheared Toroidal Flow in Tokamak Plasmas
E. G. Highcock, M. Barnes, F. I. Parra +3
First-principles numerical simulations are used to describe a transport bifurcation in a differentially rotating tokamak plasma. Such a bifurcation is more probable in a region of…
Critically balanced ion temperature gradient turbulence in fusion plasmas
M. Barnes, F. I. Parra, A. A. Schekochihin
Scaling laws for ion temperature gradient driven turbulence in magnetized toroidal plasmas are derived and compared with direct numerical simulations. Predicted dependences of turb…
Transport Bifurcation in a Rotating Tokamak Plasma
E. G. Highcock, M. Barnes, A. A. Schekochihin +3
The effect of flow shear on turbulent transport in tokamaks is studied numerically in the experimentally relevant limit of zero magnetic shear. It is found that the plasma is linea…
Turbulent transport in tokamak plasmas with rotational shear
M. Barnes, F. I. Parra, E. G. Highcock +3
Nonlinear gyrokinetic simulations have been conducted to investigate turbulent transport in tokamak plasmas with rotational shear. At sufficiently large flow shears, linear instabi…