The constraint of plasma power balance on runaway avoidance

Journal Article · Mon Jan 16 23:00:00 EST 2023 · Nuclear Fusion

DOI:https://doi.org/10.1088/1741-4326/acae38· OSTI ID:1910296

McDevitt, Christopher J.; Tang, Xian-Zhu; Fontes, Christopher J.; Sharma, Prashant; Chung, Hyun-Kyung

Abstract

In a post-thermal-quench plasma, mitigated or unmitigated, the plasma power balance is mostly between collisional or Ohmic heating and plasma radiative cooling. In a plasma of atomic mixture $\left\{n_{\alpha }\right\}$ with α labeling the atomic species, the power balance sets the plasma temperature, ion charge state distribution $\left\{n_{\alpha }^i\right\}$ with i the charge number, and through the electron temperature $T_{\mathrm{e}}$ and ion charge state distribution $\left\{n_{\alpha }^i\right\},$ the parallel electric field $E_{\parallel }.$ Since the threshold electric field for runaway avalanche growth $E_{\mathrm{a}\mathrm{v}}$ is also set by the atomic mixture, ion charge state distribution and its derived quantity, the electron density $n_{\mathrm{e}},$ the plasma power balance between Ohmic heating and radiative cooling imposes a stringent constraint on the plasma regime for avoiding and minimizing runaways when a fusion-grade tokamak plasma is rapidly terminated.

• Sponsoring Organization: USDOE Office of Science (SC), Fusion Energy Sciences (FES)
• Grant/Contract Number: 89233218CNA000001; AC02-05CH11231
• OSTI ID: 1910296
• Alternate ID(s): OSTI ID: 1906553; OSTI ID: 1960184
• Journal Information: Nuclear Fusion, Journal Name: Nuclear Fusion Journal Issue: 2 Vol. 63; ISSN 0029-5515
• Publisher: IOP Publishing
• Country of Publication: IAEA
• Language: English