Cross-Field Transport in the SOL: Its Relationship to Main Chamber and Divertor Neutral Control in Alcator C-Mod
نویسندگان
چکیده
The sources of neutrals at the outer midplane of the plasma are discussed. We find that both the flux of neutrals escaping the divertor through leaks and ion recycling at main chamber surfaces appear to contribute. The ion flux to the walls is larger than the flux entering the divertor and comparable to recycling at the divertor plate. The cause of these high wall ion fluxes is an enhancement of cross-field particle transport which gives rise to substantial convective heat transport at higher densities. We have further explored main chamber recycling and impurity transport utilizing a novel divertor ‘bypass’, which connects the outer divertor plenum to the main chamber. We find that leakage of neutrals (fuel and recycling impurities) from the divertor appears to be determined primarily by the conductance through the divertor structure, thus indicating that tight baffling would be desirable in a reactor for fuel and helium ash compression.
منابع مشابه
Cross-field plasma transport and main chamber recycling in diverted plasmas on Alcator C-Mod
Cross-field particle transport increases sharply with distance into the scrape-off layer and plays a dominant role in the ‘main-chamber recycling’ regime in Alcator C-Mod, a regime where most of the plasma particle efflux recycles on the main-chamber walls rather than flows into the divertor volume. This observation has potentially important implications for a reactor: Contrary to the ideal pic...
متن کاملParticle transport in the scrape-off layer and its relationship to discharge density limit in Alcator C-Mod*
Cross-field particle transport in the scrape-off layer ~SOL! of Alcator C-Mod @Phys. Plasmas 1, 1511 ~1994!# can be characterized by an effective particle diffusivity (Deff) that increases markedly with distance from the separatrix. As a consequence, recycling onto the main-chamber walls is large compared to plasma flows into the divertor volume. The SOL exhibits a two-layer structure: Steep gr...
متن کاملNeutrals studies on Alcator C-Mod
The high neutral densities and short neutral mean free paths in the Alcator C-Mod divertor have provided a unique testing ground for our understanding of the role of neutrals in a tokamak. The high neutral pressures found in the C-Mod divertor can only be reproduced in models by including such collisional processes as ion-neutral and neutral-neutral collisions, neutral viscosity, as well as tak...
متن کاملTransport of Particles and Energy in the Edge Plasma of the
In this thesis analysis and numerical modeling of transport in the edge plasma in the Alcator C-Mod tokamak are presented. Several important results were obtained in the course of this work, providing a new understanding of some aspects of the physical picture of the edge plasma in C-Mod. The key finding are: * Plasma escaping from the core recycles on the main chamber wall rather than in the d...
متن کاملImpurity compression and enrichment studies on Alcator C-Mod
Impurity transport has been investigated in the reactor-like conditions of the Alcator C-Mod divertor (divertor plasma density ≥1021 m-3, parallel heat flux in the SOL ≤0.5 GW-m-2). Trace amounts of the recycling impurity gases helium, neon, argon, and krypton were injected into plasmas. A residual gas analyzer that samples the private flux region of the divertor was used for divertor impurity ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2000