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Description
The TOMAS device, located at the Forschungszentrum Jülich (Germany), is dedicated to studies of wall conditioning, plasma production, and plasma-wall interaction, providing a versatile experimental environment that supports activities related to superconducting fusion devices such as W7-X, JT-60SA, and ITER.
TOMAS is a fully metallic plasma device with a major radius of 0.78 m and a minor radius of 0.26 m. The vessel's volume is approximately 1.1 m³, and its inner surface area is around 8.5 m², which can be baked to an average temperature of up to 80°C. The system features 16 toroidal magnetic field coils that provide a magnetic field on axis of up to 125 mT. The device includes a Glow Discharge system (9 kW), an Electron Cyclotron Resonance Heating system (2.45 GHz, 0.6 – 6 kW), and an Ion Cyclotron Range-of-Frequency system (10-50 MHz, up to 6 kW), producing plasmas with densities and temperatures ranging from 10¹³ to 10¹⁷ m⁻³ and 5 to 150 eV, respectively.
TOMAS is equipped with several diagnostics, including Langmuir probes, a Time-of-Flight Neutral Particle Analyzer (ToF NPA), a Residual Field Energy Analyzer (RFEA), a Microwave Interferometer, Optical Emission Spectroscopy, Quadrupole Mass Spectrometers, and video diagnostics, along with various pressure gauges. For plasma-wall interaction studies, a specially built sample load-lock system is used to expose material samples, allowing free orientation and a temperature range of up to 600°C.
This paper provides an overview of the current diagnostic capabilities of TOMAS, as well as planned upgrades. The novel aspects include the installation of an in-situ laser-induced desorption quadrupole mass spectrometry (LID-QMS) system, the extension of NPA data to deuterium, and a comparison of local density measurements from the Langmuir probes with line integrated measurements from the microwave interferometer.
Overall, TOMAS is a highly flexible device, capable of operating under a broad range of conditions without time limits regarding availability and access to the experiment.
