Plasma Recombination in Runaway Discharges in Tokamak TCABR

A new regime of runaway discharges has been observed in the TCABR tokamak. One of the most distinctive features of this regime is the e ect of plasma detachment from the limiter. This experimental fact can only be explained by the volume recombination, which requires a low-temperature plasma. The analysis of the energy and particle balance in the system plasma-relativistic runaway beam in TCABR, which takes into account only the collisional mechanism of the heat transfer from runaways to thermal electrons, predicts electron temperatures Te = 0:1 2 eV; the temperature decreases with the neutral density increase. The recombination process with the rate constant around 10 16 m/s is required for the explanation of plasma density behavior in the experiment. At present, it is diÆcult to conclude about the mechanism of recombination. More reliable and detailed experimental data, mainly about the plasma temperature, are necessary.