Expanding the role of impurity spectroscopy for investigating the physics of high-Z dissipative divertors

M. L. Reinke*, A. Meigs, E. Delabie, R. Mumgaard, F. Reimold, S. Potzel, M. Bernert, D. Brunner, J. Canik, M. Cavedon, I. Coffey, E. Edlund, J. Harrison, B. LaBombard, K. Lawson, B. Lomanowski, J. Lore, M. Stamp, J. Terry, E. ViezzerASDEX Upgrade Team, Alcator C-Mod Team, JET Contributors

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

364 Downloads (Pure)


New techniques that attempt to more fully exploit spectroscopic diagnostics in the divertor and pedestal region during highly dissipative scenarios are demonstrated using experimental results from recent low-Z seeding experiments on Alcator C-Mod, JET and ASDEX Upgrade. To exhaust power at high parallel heat flux, q > 1 GW/m2, while minimizing erosion, reactors with solid, high-Z plasma facing components (PFCs) are expected to use extrinsic impurity seeding. Due to transport and atomic physics processes which impact impurity ionization balance, so-called 'non-coronal' effects, we do not accurately know and have yet to demonstrate the maximum q which can be mitigated in a tokamak. Radiation enhancement for nitrogen is shown to arise primarily from changes in Li- and Be-like charge states on open field lines, but also through transport-driven enhancement of H- and He-like charge states in the pedestal region. Measurements are presented from nitrogen seeded H-mode and L-mode plasmas where emission from N1+ through N6+ are observed. Active charge exchange spectroscopy of partially ionized low-Z impurities in the plasma edge is explored to measure N5+ and N6+ within the confined plasma, while passive UV and visible spectroscopy is used to measure N1+-N4+ in the boundary. Examples from recent JET and Alcator C-Mod experiments which employ nitrogen seeding highlight how improving spectroscopic coverage can be used to gain empirical insight and provide more data to validate boundary simulations.

Original languageEnglish
Pages (from-to)91-99
Number of pages9
JournalNuclear Materials and Energy
Early online date15 Jul 2016
Publication statusPublished - Aug 2017
MoE publication typeA1 Journal article-refereed


Dive into the research topics of 'Expanding the role of impurity spectroscopy for investigating the physics of high-Z dissipative divertors'. Together they form a unique fingerprint.

Cite this