Effects of nitrogen seeding in a tokamak plasma

The effects of nitrogen gas seeding in the edge and scrape-off layer (SOL) regions of a tokamak plasma are studied through 2D fluid simulations using the BOUT++ code. Proper account is taken of the presence of multiple charged states of nitrogen ions due to ionization, recombination, and dissociation processes, and a self-consistent study of the interaction of these ions with the turbulent plasma in the edge and SOL regions is carried out. The self-consistent model includes the effects of polarization drifts of the main plasma and impurity ions for determining the plasma vorticity. Nitrogen seeding is found to modify the turbulence as well as to influence the profiles of the equilibrium plasma density and the electron temperature. The densities of N 3 + to N 5 + ions are found to be relatively higher than the other charged states. This is understood and further validated by a 0D simulation. The radial profiles of these impurity ions are mapped, and their radiation energy losses are estimated. The radial profile of the radiation losses is maximum near to the edge-to-SOL transition region and becomes broader in the edge region than the SOL region.

[1]  B. Duval,et al.  Nitrogen-seeded divertor detachment in TCV L-mode plasmas , 2020, Plasma Physics and Controlled Fusion.

[2]  A. Hyatt,et al.  Divertor detachment and asymmetry in H-mode operation with an ITER-like tungsten divertor in EAST , 2019, Nuclear Fusion.

[3]  J. Ghosh,et al.  Dynamics of neon ions after neon gas seeding into tokamak plasma , 2019, Nuclear Fusion.

[4]  P. Vondracek,et al.  Divertor impurity seeding experiments at the COMPASS tokamak , 2019, Nuclear Fusion.

[5]  C. Giroud,et al.  Using EDGE2D-EIRENE to simulate the effect of impurity seeding and fueling on the upstream electron separatrix temperature , 2019, Nuclear Materials and Energy.

[6]  P. Atrey,et al.  Overview of operation and experiments in the ADITYA-U tokamak , 2019, Nuclear Fusion.

[7]  J. Svensson,et al.  Radiative edge cooling experiments in Wendelstein 7-X start-up limiter campaign , 2019, Nuclear Fusion.

[8]  B. Duval,et al.  Progress toward divertor detachment on TCV within H-mode operating parameters , 2019, Plasma Physics and Controlled Fusion.

[9]  Dezhen Wang,et al.  The impact of neon-seeding location on the divertor plasma in EAST , 2018, Fusion Engineering and Design.

[10]  Y. Feng,et al.  Three-dimensional impurity transport modeling of neon-seeded and nitrogen-seeded LHD plasmas , 2018, Plasma Physics and Controlled Fusion.

[11]  F. Ryter,et al.  Modelling of nitrogen seeding experiments in the ASDEX Upgrade tokamak , 2018 .

[12]  P. Kaw,et al.  Influence of hot and cold neutrals on scrape-off layer tokamak plasma turbulence , 2018 .

[13]  A. Kukushkin,et al.  Physics of ultimate detachment of a tokamak divertor plasma , 2017, Journal of Plasma Physics.

[14]  M. Wischmeier,et al.  Investigation of the effects of impurity seeding under different magnetic configurations in L-mode plasma in EAST tokamak , 2017 .

[15]  T. Petrie,et al.  Effects of low-Z and high-Z impurities on divertor detachment and plasma confinement , 2017 .

[16]  T. Morisaki,et al.  Toroidally symmetric/asymmetric effect on the divertor flux due to neon/nitrogen seeding in LHD , 2017 .

[17]  J. Contributors,et al.  High power neon seeded JET discharges: Experiments and simulations , 2017 .

[18]  A. A. Mavrin.  Radiative Cooling Rates for Low-Z Impurities in Non-coronal Equilibrium State , 2017 .

[19]  V. Rohde,et al.  Ammonia production in nitrogen seeded plasma discharges in ASDEX Upgrade , 2015 .

[20]  J. Schweinzer,et al.  Impurity seeding for tokamak power exhaust: from present devices via ITER to DEMO , 2013 .

[21]  P. Ghendrih,et al.  Influence of neutral particles on scrape-off layer turbulence with application to the interpretation of fast camera data , 2013 .

[22]  L. Méndez,et al.  Ab initio calculation of charge transfer in proton collisions with N 2 , 2012 .

[23]  D. P. Coster,et al.  Detachment physics in SOLPS simulations , 2011 .

[24]  C. Hegna,et al.  Determining the Bohm criterion in plasmas with two ion species , 2011 .

[25]  D. Russell,et al.  Reduced model simulations of the scrape-off-layer heat-flux width and comparison with experiment , 2011 .

[26]  P. Snyder,et al.  Simulation of edge localized modes using BOUT++ , 2010, 1008.4554.

[27]  A. Sen,et al.  Edge and scrape-off layer tokamak plasma turbulence simulation using two-field fluid model , 2005 .

[28]  Abhijit Sen,et al.  Simulation of plasma transport by coherent structures in scrape-off-layer tokamak plasmas , 2004 .

[29]  G. Staebler,et al.  Effects of impurity seeding in DIII-D radiating mantle discharges , 2002 .

[30]  Y. Sarazin,et al.  Intermittent particle transport in two-dimensional edge turbulence , 1998 .

[31]  Douglass E. Post,et al.  Steady-state radiative cooling rates for low-density, high-temperature plasmas , 1977 .