#### V.H. Hall-Chen F.I. Parra J.C. Hillesheim J. Ruiz Ruiz N.A. Crocker P. Shi H.S. Chu S.J. Freethy L.A. Kogan W.A. Peebles Q.T. Pratt T.L. Rhodes K. Ronald R. Scannell D.C. Speirs S. Storment J. Trisno

Doppler reflectometry, or the Doppler backscattering (DBS) diagnostic, enables the measurement of turbulent density fluctuations of intermediate length scales, typically $10 gtrsim k_perp rho_i gtrsim 1$; here $k_perp$ is the turbulence’s wavenumber and $rho_i$ is the ion gyroradius. The backscattered power is proportional to the power of the tur…

Preprint#### S.M. Kaye J.W. Connor C.M. Roach

In this paper, we review the confinement and transport properties observed and predicted in low aspect ratio tokamaks, or spherical tokamaks (STs), which can depart significantly from those observed at higher aspect ratio. In particular, thermal energy confinement scalings show a strong, near linear dependence of energy confinement time on toroidal…

Preprint Published#### S B L Chislett-McDonald E Surrey J Naish A Turner D P Hampshire

All high field superconductors producing magnetic fields above 12 T are brittle. Nevertheless, they will probably be the materials of choice in commercial tokamaks because the fusion power density in a tokamak scales as the fourth power of magnetic field. Here we propose using robust, ductile superconductors during the reactor commissioning phase i…

Preprint#### S. L. Dudarev P. Liu D. A. Andersson C. R. Stanek T. Ozaki C. Franchini

Unraveling the complexity of non-collinear magnetism in materials with strongly correlated electrons is a considerable task that requires developing and applying state of the art theories and computational methods. Using the Coury model Hamiltonian, which includes spin and orbital degrees of freedom and generalizes the collinear Stoner Hamiltonian,…

Preprint#### T. Adkins A. A. Schekochihin P. G. Ivanov C. M. Roach

Electromagnetic instabilities and turbulence driven by the electron-temperature gradient are considered in a local slab model of a tokamak-like plasma, with constant equilibrium gradients (including magnetic drifts but no magnetic shear). The model describes perturbations at scales both larger and smaller than the electron inertial scale de

Preprint#### Guanqi Dong Yueqiang Liu Xi Chen Guangzhou Hao Yi Liu Shuo Wang Neng Zhang Guoliang Xia

In quiescent H-mode (QH-mode) regime, edge harmonic oscillations (EHOs) are believed to provide necessary radial transport to prevent occurrence of large edge localized modes. A systematic modeling study is performed here on the low-n EHOs in a DIII-D QH-mode plasma [Chen et al. 2016 Nucl. Fusion 56 076011], by utilizing the MARS-Q code [Liu et a…

Preprint Published#### J. Simpson D. Moulton C. Giroud D. Harting G. Corrigan M. Groth JET Contributors

EDGE2D-EIRENE simulations of upstream density and radiative power scans in JET H-mode type plasmas in vertical target predict a linear relationship between the electron and ion temperatures, and power across the separatrix. This is in contradiction to the two-point model equations which states that the upstream temperature scales at the po…

Preprint Published#### J F Parisi F I Parra C M Roach C Giroud W Dorland D R Hatch M Barnes J C Hillesheim N Aiba J R Ball P G Ivanov

Local linear gyrokinetic simulations show that electron temperature gradient (ETG) instabilities are the fastest growing modes for kyρi >~ 0.1 in the steep gradient region for a JET pedestal discharge (92174) where the electron temperature gradient is steeper than the ion temperature gradient. Here, ky is the wa…

Preprint Published#### M. R. Hardman M. Barnes C. M. Roach

Magnetised plasma turbulence can have a multiscale character: instabilities driven by mean temperature gradients drive turbulence at the disparate scales of the ion and the electron gyroradii. Simulations of multiscale turbulence, using equations valid in the limit of infinite scale separation, reveal novel cross-scale interaction mechanisms in …

Preprint Published#### Bogdan Hnat Nick Walkden The MAST Team

We study the amplitude modulation of the radial electric field constructed from the Langmuir probe plasma potential measurements at the edge of MAST. The Empirical Mode Decomposition technique is applied, which allows us to construct fluctuations on temporal scales of plasma turbulence, the Geodesic Acoustic Mode and these associated with the res…

Preprint Published