H-mode confinement is most likely required to achieve economic fusion power production in toroidal plasmas. Since the discovery of the L-H transition in 1982, significant progress has been made in elucidating key aspects of the transition dynamics, however a comprehensive physics-based transition model is still elusive. Over the last decade, substantial advances in diagnostics have provided fluctuation and flow data with unprecedented spatial and temporal resolution in the plasma edge layer, greatly improving our understanding of L-H transition dynamics. In parallel, multiple reduced transition models have been devised and in some cases tested based on experimental data. Initial first principles Gyrokinetic modeling of the edge turbulence properties in the L-mode phase leading up to the transition, and the transition dynamics has started.
Physics-based predictive models for the L-H transition power threshold are urgently needed to assess and minimize auxiliary power requirements in future burning plasma experiments such as ITER. In particular, the observed isotopic dependence of the L-H power threshold (presently not understood), is greatly relevant for H-mode access during initial non-nuclear ITER operations. The implications of applied non-axisymmetric magnetic fields for the L-H power threshold are important with regards to H-mode ELM control and the required error field compensation. Differences in L-H transition dynamics and power threshold scaling in ion- vs. electron-heat dominated plasmas, and in plasmas with different divertor configuration and plasma-facing materials are of particular interest.
This Plasma Physics and Controlled Fusion Special Issue on L-H Transition Physics - accompanying the 25th Joint EU-US Transport Task Force Meeting - aims to capture recent progress with regards to experimental work, modelling and simulation efforts, and multi-machine database analysis and scaling.
The window for submissions is 1 October 2021 until 30 April 2022.
All articles should be submitted through the PPCF online submission system. In the first step of the online form, under 'Manuscript Type' please select 'Special Issue Article' and select 'Special Issue on L-H Transition Physics' from the drop-down box.
Special Issues in PPCF are published on an incremental basis, with articles published and collected on this landing page as soon as they are ready, meaning there is no delay to articles submitted earlier in the window. Accepted papers will be made available online within 24 hours of acceptance, with a citable DOI. There are no page charges for publishing on a subscription basis in PPCF, although a paid open access option is available.