Speaker
Description
The concept on which the OLMAT project is basically the use of the Neutral Beams (NBI) used for the heating of the plasma in TJ-II for the irradiation of materials at relevant powers for the DEMO divertor, up to 20 MW /m2. At present, two NBI systems are available, capable of injecting up to 700KW into the plasma. The beam, generated by extraction of hydrogen ions from a plasma created for this purpose and subsequently neutralized, presents a Gaussian distribution of power with a width at half height (FWHM) of about 15 cm at the position of the plasma, originating a circular area of about 25 cm in diameter of powers greater than 10MW/m2 geometrically limited by openings inserted ad hoc. In its routine operation with TJ-II plasmas, the beams are generated every 10 minutes approximately, but if the power supply of the TJ-II coils is used only to feed the NBI power supply, the repetition frequency of "shots" NBI It can be increased up to one pulse every two minutes. In this way the materials can be exposed to the thermal loads produced by the NBI hundreds of times each day of operation. In these circumstances it is expected that the thermal-mechanical fatigue of the material can be tested much more quickly than that of any current device, although the duration of the NBI pulse is limited to about 150-200 ms. The elimination of the neutralizer, mandatory in the production of a single beam of neutrals in the presence of the magnetic fields of TJ-II, can increase the real power incident on the material by 35%, although its effect on the creation of a highly radiative plasma on the surface of the material is yet to be explored.
