From the middle of the XX century there has been conducted the research of the problem of controlled thermonuclear fusion as a way of getting energy without practical limitations in sources. The most perspective method of its technical realization is power station on the basis of tokamak, a device for magnetic containment of high-temperature plasma. Project ITER is created on the way to the first commercial thermonuclear reactor in the Cadarache research centre (France), and Russia is one of participating countries. Physical research on tokamaks, which allows work out its separate engineering physical aspects, is conducted in support of the ITER program.

A student of the MEPhI “Plasma physics” Department Nikita Soloviev told us about his research activity at tokamak T-10 in the Laboratory of research of transportation processes in plasma.

• My activity is connected with diagnostics of electron-cyclotron radiation (ECR) – electromagnetic waves, created by plasma electrons, revolving around magnetic field lines. It carries information about a number of plasma paramtres in a tokamak. In practice, the most important of these parameters is the temperature of electrons as function of coordinates and time, which can be defined by electron-cyclotron radiation with good time and spatial resolution. Measuring of electronic temperature is necessary for definition of efficiency of plasma heating, analysis of instabilities, finding out the nature of processes of heat and particle transfer in plasma, in particular, turbulent transfer. It is crucial for realization of energetically efficient thermonuclear reactor.
• Which problems in particular do you study?
• The diagnostics of electron-cyclotron radiation is standard at modern tokamaks, but getting data about electronic temperature with the help of this diagnostics is connected with a lot of problems. Solving of these problems is one of tasks which our laboratory is conducting.

At first, there is a problem of right physical interpretation of experimental data. Electron-cyclotron radiation is delivered to the measuring equipment in “distorted” form: it is partially deflected by dense plasma, mixed with radiation of beams of accelerated electrons, is reflected from the walls of vacuum camera, is shifted by frequency in connection with Doppler effect and other phenomena. The     receiving equipment also has a number of peculiarities, which are a source of additional distortion of measurings. At present, we have a list of known physical phenomena that make interpretation of the experimental data difficult, but to take into account these phenomena, development of special data processing algorithms is required. My main task is the implementation of such algorithms on T-10.

Secondly, technological difficulties arise. The ECR in tokamaks, as a rule, is in the range of ultrahigh frequencies (SHF). The production of the necessary devices for registration of microwave radiation in Russia needs to be developed. We do not deal directly with the manufacture of devices, but we are in close contact with domestic manufacturers, carrying out tests, adjustment and operation of equipment.

Feedback from our side allows manufacturers to make modifications to the equipment necessary to effectively use it for microwave plasma diagnostics. This should make it possible to provide diagnostic complexes for new experimental facilities, such as T-15, which is under construction, at the appropriate level by domestic manufacturers of instruments.

We are one of the few domestic laboratories that have a measuring stand for testing microwave receivers. It is actively used for monitoring the parameters of diagnostic equipment.

- What will be the result of your work?

- These studies are of a purely practical nature. The tangible result of my contribution to them will be a set of algorithms and their implementation in the form of computer programs that will automatically take into account all relevant characteristics of equipment and plasma parameters to obtain reliable data on the electron temperature. Prototypes of these programs are currently being tested at T-10. Successful implementation of them will improve the efficiency of monitoring the experimental parameters for the T-10 and future thermonuclear installations.