First plasmas in the TJ-II flexible Heliac

Abstract

First plasmas have been successfully achieved in the TJ-II stellarator using electron cyclotron resonance heating (f = 53.2 GHz, P ECRH = 250 kW). Initial experiments have explored the TJ-II flexibility in a wide range of plasma volumes, different rotational transform and magnetic well values. In this paper, the main results of this campaign are presented and, in particular, the influence of plasma wall interaction phenomena on TJ-II operation is discussed briefly.

Synthesis and design of waveguide band-stop filters without out-of-band spurious responses for plasma diagnosis

“…In the TJ-II stellarator [9], plasmas are created and heated by Electron Cyclotron Heating (ECH) working at 53.2 GHz with a power of up to 600 kW [10]. Using this heating method, the accessible plasma density is limited by the cut-off density (n cutoff = 1.75 10 19 m −3 ).…”

Optimization of energy confinement in the 1/ν regime for stellarators

“…Therefore, the optimization results are valid for the equilibria with a small plasma pressure or for devices with weak influence of the finite plasma pressure on the equilibrium magnetic configuration, e.g. for ''heliac-type" devices like TJ-II [15]. These conditions allow for optimization fully in real space without any restrictions to the complexity of the magnetic field.…”

“…The optimization scheme and the necessary adaption for the presented tool SORSSA are outlined in Section 3. In Section 4 an application to the ''heliac-type" stellarator TJ-II [15] is presented. This device is well suited for this purpose, because it has a very high equilibrium beta, and therefore the plasma position and shape change very little with increasing beta.…”

Overview of the TJ-II remote participation system

“…The TJ-II remote participation system arose as a consequence of the need to upgrade the data acquisition system of the TJ-II stellarator [1]. The challenge was to use the most advanced and up to date tools in order to develop an open and scalable architecture powerful enough to be applied to very demanding environments as well as being suitable for remote participation (RP).…”