A 0D stationary model for the evaluation of the degree of detachment on the divertor plates

A 0D analytical stationary model to estimate the degree of detachment on the divertor plates is derived, starting from previous works of Igitkhanov (Igitkhanov et al 1994 21st EPS (Montpellier) ECA v.18B, 1995 22th EPS (Bournemouth) ECA v.19C, Igitkhanov 2014 KIT Sci. Rep. 7661). It accounts for heat convection, conduction, impurity radiation and contains a simplified balance for the neutrals. The upstream particle flux (or, alternatively, the density upstream n up ), the heat flux in the scrape-off layer (SOL) q up and the impurity concentrations are required as input, whereas the temperatures at the plate and at the separatrix are not fixed a priori. The routine has been mainly developed for system codes, or more in general for scopy studies in the framework of the preliminary design phase for the reactor DEMO, its simplicity being therefore justified by the purpose of keeping the calculation times as low as possible. A calibration against a more detailed 1D routine (Kallenbach et al 2016 Plasma Phys. Control. Fusion 58 045013) has been performed, finding a reasonable agreement. Furthermore, a coupling of the model with the 1.5D transport code ASTRA (Pereverzev 1991 IPP Report 5/42, Fable et al 2013 Plasma Phys. Control. Fusion 55 124028) to illustrate its possible usage is also presented.

[1]  P. Stangeby,et al.  Experimental divertor physics , 1997 .

[2]  T. Petrie,et al.  Scaling radiative divertor solutions to high power in DIII-D , 2012 .

[3]  David Ward,et al.  “PROCESS”: A systems code for fusion power plants—Part 1: Physics , 2014 .

[4]  B. N. Bazylev,et al.  The quantification of the key physics parameters for the DEMO fusion power reactor and analysis of the reactor relevant physics issues (KIT Scientific Reports ; 7661) , 2014 .

[5]  G. V. Pereverzew,et al.  ASTRA. An Automatic System for Transport Analysis in a Tokamak. , 1991 .

[6]  L. Lengyel.  Analysis of Radiating Plasma Boundary Layers , 1981 .

[7]  R. Dux,et al.  Analytical calculations for impurity seeded partially detached divertor conditions , 2016 .

[8]  S. A. Self,et al.  Static Theory of a Discharge Column at Intermediate Pressures , 1966 .

[9]  David Ward,et al.  On the physics guidelines for a tokamak DEMO , 2013 .

[10]  Tadashi Sekiguchi,et al.  Plasma Physics and Controlled Nuclear Fusion Research , 1987 .

[11]  David Ward,et al.  Modelling of pulsed and steady-state DEMO scenarios , 2015 .

[12]  T. Eich,et al.  Inter-ELM power decay length for JET and ASDEX upgrade: measurement and comparison with heuristic drift-based model. , 2011, Physical review letters.

[13]  M. Gadomska,et al.  Overview of EU DEMO design and R&D activities , 2014 .

[14]  I. Hutchinson.  Thermal front analysis of detached divertors and MARFEs , 1994 .

[15]  P. Stangeby.  The Plasma Boundary of Magnetic Fusion Devices , 2000 .

[16]  J. Contributors,et al.  Scaling of the tokamak near the scrape-off layer H-mode power width and implications for ITER , 2013 .

[17]  R. Neu,et al.  DEMO divertor limitations during and in between ELMs , 2014 .