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UKAEA-STEP-CP(26)022025
The nonlinear transition to large heat fluxes in local gyrokinetic simulations of electromagnetic turbulence in STEP (a conceptual spherical tokamak power plant) is investigated. Consistent with results reported elsewhere, the onset of enhanced transport is shown to depend on a critical value of q2βe and appears closely connected to a limit on β…
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UKAEA-STEP-PR(25)332024
A quasi-linear reduced transport model is developed from a database of high-β electromagnetic nonlinear gyrokinetic simulations performed with Spherical Tokamak for Energy Production (STEP) relevant parameters. This reduced transport model is based on a quasi-linear metric computed from linear gyrokinetic simulations and accounts for the effect of…
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UKAEA-STEP-PR(25)252024
This paper discusses the importance of parallel and perpendicular magnetic field perturbations in gyrokinetic simulations of electromagnetic instabilities and turbulence at mid-radius in the burning plasma phase of the conceptual high-β, reactor-scale, tight-aspect- ratio tokamak STEP. Previous studies have revealed the presence of unstable hybrid…
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UKAEA-CCFE-PR(24)2332024
Starting from the assumption that saturation of plasma turbulence driven by temperature-gradient instabilities in fusion plasmas is achieved by a local energy cascade between a long-wavelength outer scale, where energy is injected into the fluctuations, and a small-wavelength dissipation scale, where fluctuation energy is thermalized by particle…
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UKAEA-CCFE-CP(25)112023
Retention of tritium in structural materials of a fusion reactor is a concern for tritium accountancy, maintenance, and decommissioning. Plasma facing materials will be exposed to high temperatures, neutron damage and hydrogen isotopes. The damage caused by these conditions is a large area of exploration for fusion, with many questions still to…
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UKAEA-CCFE-PR(24)2202023
Spherical tokamaks (STs) have many desirable features that make them an attractive choice for a future fusion power plant. Power plant viability is intrinsically related to plasma heat and particle confinement and this is often determined by the level of micro-instability driven turbulence. Accurate calculation of the properties of turbulent micro-…
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UKAEA-CCFE-PR(24)2172023
Fusion energy offers the potential for a near limitless source of low-carbon energy and is oftenregarded as a solution for the world’s long-term energy needs. To realise such a scenario requiresthe design of high-performance fusion reactors capable of maintaining the extreme conditionsnecessary to enable fusion. Turbulence …
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UKAEA-STEP-PR(23)112023
We present herein the results of a linear gyrokinetic analysis of electromagnetic microinstabilites in the conceptual high−β, reactor-scale, tight-aspect-ratio tokamak STEP (Spherical Tokamak for Energy Production, https://step.ukaea.uk). We examine a range of flux surfaces between the deep core and the pedestal top for the two candidate flat…
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UKAEA-STEP-PR(23)102023
In this work, we present the results of first-of-their-kind nonlinear local gyrokinetic simulations of electromagnetic turbulence at mid-radius in the burning plasma phase of the conceptual high-β, reactor-scale, tight-aspect-ratio tokamak STEP (Spherical Tokamak for Energy Production). A prior linear analysis in D.Kennedy et al. submitted to Nucl…
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UKAEA-CCFE-PR(23)1412023
In this paper, we summarize our recent work on gyrokinetic applications in electron- positron and non-neutral plasma. The electrostatic stability of electron-positron plasmas was investigated in dipole and slab geometry, with and without ion admixture. The gyrokinetic dispersion relation was derived and, for the slab case, extended to non-neutra…
Showing 1 - 10 of 15 UKAEA Paper Results