Showing 1 - 10 of 32 Journals Results

2021

UKAEA-STEP-PR(21)01

#### B.S. Patel D. Dickinson C.M. Roach H.R. Wilson

#### Spherical tokamaks (STs) have been shown to possess properties desirable for a fusion power plant such as achieving high plasma β and having increased vertical stability. To understand their confinement properties in a reactor relevant regime a 1GW fusion power spherical tokamak plasma equilibrium was analysed using linear gyrokinetics to determin…

Preprint Purchase2021

UKAEA-CCFE-PR(21)35

#### A R Field P Carvalho D Frigione L Garzotti Hyun-Tae Kim M Lenholm E Lerche J Mailloux F Rimini C M Roach M Sertoli G Szepeisi D van Eester.

#### Sustained operation of high-performance, ITER-baseline scenario plasmas at the high levels of input power (~< 40MA) required to achieve ~ 15 MW of D-T fusion power in JET-ILW requires careful optimisation of the fuelling to avoid an unacceptable disruption rate due to excessive radiation, primarily from W impurities, which are sputter…

Preprint Published2020

UKAEA-CCFE-PR(20)21

#### 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 Published2019

UKAEA-CCFE-PR(20)111

#### 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 …

Preprint2019

UKAEA-CCFE-PR(19)21

#### Luca Garzotti C. Challis R. Dumont D. Frigione J. Graves E Lerche J. Mailloux M. Mantsinen F. Rimini F. Casson A. Czarnecka J. Eriksson R. Felton L. Frassinetti D. Gallart J. Garcia C. Giroud E. Joffrin H.-T. Kim N. Krawczyk M. Lennholm P. Lomas C. Lowry L. Meneses I. Nunes C. M. Roach M. Romanelli S. Sharapov S. Silburn A. Sips E. Stefanikova M. Tsalas D. Valcarcel M. Valovic JET contributors

#### The JET exploitation plan foresees D-T operations in 2020 (DTE2). With respect to the first D-T campaign in 1997 (DTE1), when JET was equipped with a carbon wall, the experiments will be conducted in presence of a beryllium-tungsten ITER-like wall (ILW) and will benefit from an extended and improved set of diagnostics and higher additional heating …

Preprint Published2018

UKAEA-CCFE-PR(19)13

#### M. R. Hardman M. Barnes C. M. Roach F. I. Parra

#### 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 and the consequent disparity of the ion and electron thermal gyroradii and thermal speeds. Direct simulations of this turbulence that include both ion and electron space-ti…

Preprint Published2018

UKAEA-CCFE-PR(18)20

#### JW Connor RJ Hastie C Marchetto CM Roach

#### Starting from expressions in Connor et al. (1988), we derive a one-dimensional tearing equation similar to the approximate equation obtained by Hegna & Callen (1994); Nishimura et al. (1998), but for more realistic toroidal equilibria. The intention is to use this approximation to explore the role of steep H-mode pedestals, bootstrap currents a…

Preprint Published2017

CCFE-PR(17)49

#### P. A. Abdoul D. Dickinson C. M. Roach H. R. Wilson

#### In this work, using solutions from a local gyrokinetic flux-tube code combined with higher order ballooning theory, a new analytical approach is developed to reconstruct the global linear mode structure with associated global mode frequency. In addition to the isolated mode (IM), which usually peaks on the outboard mid-plane, the higher order ballo…

Preprint Published2016

CCFE-PR(16)48

#### G. J. Colyer A. A. Schekochihin F. I. Parra C. M. Roach M. A. Barnes Y. C. Ghim W. Dorland

#### In electrostatic simulations of MAST plasma at electron-gyroradius scales, using the local flux-tube gyrokinetic code GS2 with adiabatic ions, we find that the longtime saturated electron heat flux (the level most relevant to energy transport) decreases as the electron collisionality decreases. At early simulation times, the heat flux quasisatura…

Preprint Published2016

CCFE-PR(16)17