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The main task of the Section for the Management of Large Experimental Facilities
is to ensure that the Frascati Tokamak Upgrade (FTU) machine operates reliably
including control and acquisition of engineering & physical data during
the nuclear fusion experiment.
(See also FTU Multimedial and intranet web sites FTU – FTU-OnLine)
Among its duties, particularly relevant are the optimization of techniques to reduce the plasma contamination using different elements instead of the normal working gasses (Deuterium and/or Hydrogen). In this line of research, but with more ambitious targets, is studying of new first wall materials, like liquid metals, potentially interesting for future fusion reactors.Top view of FTU
FTU is a medium-size tokamak machine with a high toroidal magnetic field (80,000 Gauss). For such a high field, a continuous current of 37,800 Ampere per 1.5 seconds has to pass through the toroidal windings. As all the FTU windings are copper coils, their resistivity has to be lowered in order to considerably decrease dissipation through the Joule effect and hence avoid damage to the coils. The only way to do this is to constantly keep the coils at the operating temperature of liquid nitrogen, that is, about -196°C.
|Plasma major radius||0.935||m|
|Plasma minor radius||0.31||m|
|Maximum Plasma Current||1.6||MA|
|Toroidal Magnetic Field||8||T|
|Toroidal Field flat-top duration||1.5||s|
|Load Assembly weight||˜90||t|
|Toroidal Field Energy||160||MJ|
|Poloidal Field Energy||200||MJ|
|Pulse Repetition Rate: 1 pulse every 20 min.|
The Machine group supervises all the activities concerning the machine (torus) and its subsystems. The service also interfaces with the diagnostic apparatus and radiofrequency plants (competence of the “Magnetic Confinement Physics” Section). (more »)
The Electrical Power Supplies group manages two large motor flywheel generators (MFGs), which have unique characteristics, and all the intermediate rectification bridges and thyristors, switches, isolators and relative control electronics. (more »)
The Data Control and Acquisition group guarantees real-time control and computerised monitoring of all the plants (including the radiofrequency plants), as well as the automatic operation sequences and fast acquisition of physics and engineering data. (more »)
To reduce the plasma contamination, together with the classical techniques of vacuum vessel cleaning like "baking" and "glow discharge", other particular conditioning techniques by thin film deposition of different materials have been developped and implemented inside FTU, like titanium (titanization), boron (boronization) end lately litium (litization). In this last case, a "liquid litium limiter" in contact with plasma has been used to produce and deposit litium atoms on the inner walls of FTU vacuum chamber.
As FTU is an experimental facility, it requires continuous improvement and updating as well as precise maintenance and reporting programmes to enable it to operate with the full reliability shown by the statistical data in the following :
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