Plasma Position Control using Electromagnetic Waves

An IPFN and IPP team led by IPFN researcher Jorge Santos (Scientific Coordinator) has, for the second time, demonstrated the viability of using electromagnetic waves in replacement of standard magnetic measurements for controlling the position of a fusion plasma. In this new demonstration, the follow-up to the breakthrough experiment performed at the ASDEX Upgrade by the same team in 2011, a second broad-band O-mode reflectometer at the high-field side (HFS) of the tokamak was used in addition to the originally used low-field side (LFS) one. The joint operation of both reflectometers in the feedback control experiments allowed the researchers to test the technique at two of the four lines of sight of the future ITER plasma position reflectometer (PPR), presently being designed by a consortium led by IPFN. The development of this technique is essential for long pulsed ITER like machines, and next step fusion reactors, such as DEMO, where the standard magnetic based control might prove unreliable or even impossible to implement.

In the last 30 years, IPFN has developed a leading edge engineering expertise in the design, implementation and exploitation of micro-wave diagnostics. The international recognition of this expertise is evidenced by the large number of diagnostics deployed by the team on past and present experimental devices: ASDEX (Germany), ASDEX Upgrade (Germany), ISTTOK (Portugal), JET (U.K.), MAST (U.K.), TJ-II (Spain), TCA-Br (Brasil), and COMPASS (Czech Republic). Leveraging the knowledge gained namely on ITER relevant fusion tokamaks such as ASDEX-Upgrade and JET, IPFN has been increasingly engaging in international collaborations such as the one responsible for the recently commissioned multichannel X-mode reflectometer, on ASDEX Upgrade, or the IPFN led consortium (IPFN, CIEMAT & IFP) responsible for the design of the ITER PPR (F4E-FPA-375 “Plasma Position Reflectometry System”).