The upgraded TOMAS device: A toroidal plasma facility for wall conditioning, plasma production, and plasma–surface interaction studies

Abstract

The Toroidal Magnetized System device has been significantly upgraded to enable development of various wall conditioning techniques, including methods based on ion and electron cyclotron (IC/EC) range of frequency plasmas, and to complement plasma-wall interaction research in tokamaks and stellarators. The toroidal magnetic field generated by 16 coils can reach its maximum of 125 mT on the toroidal axis. The EC system is operated at 2.45 GHz with up to 6 kW forward power. The IC system can couple up to 6 kW in the frequency range of 10 MHz-50 MHz. The direct current glow discharge system is based on a graphite anode with a maximum voltage of 1.5 kV and a current of 6 A. A load-lock system with a vertical manipulator allows exposure of material samples. A number of diagnostics have been installed: singleand triple-pin Langmuir probes for radial plasma profiles, a time-of-flight neutral particle analyzer capable of detecting neutrals in the energy range of 10 eV-1000 eV, and a quadrupole mass spectrometer and video systems for plasma imaging. The majority of systems and diagnostics are controlled by the Siemens SIMATIC S7 system, which also provides safety interlocks.

Comparative analysis of the plasma parameters of ECR and combined ECR + RF discharges in the TOMAS plasma facility

“…where Z is the ion charge state for helium and hydrogen (hydrogen can be present in the discharge as a residual minority in the vacuum system) ions is not satisfied. However, a regime of high cyclotron harmonics (HCH) ω RF = nω ci (n number harmonic) is possible [27,29,48]. With the values of B and f RF of these experiments, the HCH mode can be for H + (n > 13), He 2+ (n > 27) and He + (n > 54).…”

“…The toroidal magnetic field is generated by a magnetic system consisting of 16 water-cooled coils. The magnetic system was powered by a DC power supply with the maximum output current of 2.2 kA, delivering a magnetic field on-axis up to 0.125 T. The value of the magnetic field is proportional to the coil current I c [27]. The accuracy of the power supply current control is ∼1%.…”

“…In [48] it was shown that for the HCH mode the electrons absorb more than 90% of the incoming power via electronneutral collisions for both the Fast Wave and the Ion Bernstein Wave. The HCH mode for TOMAS was discussed in [27,29].…”

Fusion Research in Stellarator Department of Ipp NSC Kipt

“…The Toroidal Magnetized System device has been significantly upgraded to enable development of various wall conditioning techniques, including methods based on ion and electron cyclotron (IC/EC) range of frequency plasmas, and to complement plasma-wall interaction research in tokamaks and stellarators [13]. The toroidal magnetic field generated by 16 coils can reach its maximum of 125 mT on the toroidal axis.…”

Overview of TOMAS plasma diagnostics

“…As wall conditioning plasmas are much less energetic than fusion plasmas, it is necessary to use dedicated diagnostic methods to study plasma wall interactions, as well as the plasma itself. The TOroidal MAgnetized System (TOMAS) plasma facility aims at complementary research on wall conditioning methods, plasma production and plasma-surface interaction studies for superconducting devices such as W7-X and ITER [3]. This paper presents an overview of the TOMAS plasma diagnostics.…”