Department of Plasma Physics and Technology: Overview

Full text: In 2004 our research activities in Dept. P-V were concentrated on the continuation of previous studies in the field of plasma physics and controlled nuclear fusion. New investigations were also undertaken, particularly in the field of plasma technology. The main tasks of the research activities were as follows: 1. Studies of physical phenomena in pulsed discharges producing dense magnetized plasma; 2. Development of methods and tools for high-temperature plasma diagnostics; 3. Research in the field of plasma technologies. In a frame of the first task the correlation of pulsed X-rays and e-beams was investigated in PF-type discharges, mostly in the MAJA-PF facility. Measurements of instants when X-ray spectral lines are emitted from different hot-spots, enabled us to perform an analysis of changes in the polarization of those lines, to correlate selected spectral peaks with the appearance of corresponding hot-spots, and to estimate changes of the electron temperature. It was shown that the highly-ionized Ar-lines are really emitted from individual hot-spots, and the maxima of these lines are well correlated with the appearance and duration of such dense plasma micro-regions. In collaboration with IFPiLM in Warsaw and CVUT in Prague experimental research on the pulsed emission of X-rays and fusion-produced neutrons was performed with the use of different solid targets within the PF-1000 facility. A summary of our joint research on physics of PF-type discharges was presented at an international conference in Prague. A detailed analysis of the main problems connected with high-current pulsed discharges of the PF-type was presented at a conference in Tomsk, and progress in studies carried out with the large PF-1000 facility was summarized in an invited talk given at the conference in Alushta. To initiate an active participation in the EURATOM fusion program, we elaborated a proposal of the adaptation of some diagnostic techniques to studies of high-temperature plasma within magnetic traps. That proposal was presented at the conference in Prague and at a seminar at Cadarache. Also a detailed study of characteristics of discharges within PF-360 and PF-1000 facilities was performed, and temporal changes of the neutron emission anisotropy were investigated. Another experimental task was the development of plasma diagnostic techniques. Investigations of selected solid-state nuclear track detectors (SSNTDs) were continued. Calibration studies were extended to measure the depth of micro-craters produced by various ions. The SSNTDs were applied in different plasma experiments, e.g. in the TEXTOR machine in Juelich and the PALS experiment in Prague. Additional calibration measurements were also performed by means of mono-energetic ion beams from an accelerator. The calibrated detectors were used for preliminary measurements of fast (3 MeV) protons from fusion reactions in the PF-1000 facility. The calibration measurements for low-energy (50-300 keV) protons were carried out by means of a Thomson-type spectrometer at the IBIS facility. Results were reported at international conferences in Uppsala, Barcelona, Kudowa Zdroj and Cracow. The development of diagnostic methods also included time-resolved optical spectroscopy of pulsed plasma-ion streams. In cooperation with researchers from KIPT in Kharkov and CVUT in Prague, two series of detailed spectroscopic measurements were performed within the PF-1000 facility and ''exploding-wire'' experiment at IFPilM in Warsaw. An interaction of the pulsed plasma-ion streams with different targets, and particularly with hydrogen getters, was studied in the RPI-IBIS facility in Swierk. Results of spectroscopic studies were reported at international conferences in Kiev, Prague, St. Petersburg and Alushta. As for technological studies, efforts were devoted to develop ultra-high vacuum arc-technology for deposition of thin Nb-layers upon internal surfaces of RF accelerator cavities. The modernization of a prototype set-up (equipped with a cylindrical cathode) was performed and a new triggering system (based on Nd-YAG laser) was tested in Swierk. In the bilateral collaboration with the Tor Vergata University in Rome, experimental studies were performed with the use of a planar-cathode system. A magnetic filter system was tested and the Nb-coated samples were compared with the samples of bulk Nb. Technological research also included studies of a coaxial accelerator with squirrel-cage electrodes used for the impulse plasma deposition (IPD). Other studies of plasma-ion techniques for material engineering were performed in collaboration with the P-IX Department (see chapter IX of this Report). The most important achievements of the P-V Department in 2004 were as follows: 1. Detailed spectroscopic measurements of plasma discharges in different experimental facilities (IBIS, PF-360 and PF-1000), and the demonstration that impurities appear with a delay depending on the electrode configuration, gas conditions and target parameters; 2. Measurements of the emission anisotropy of fast neutrons emitted from fusion reactions in PF-360 and PF-1000 devices, and a comparative analysis of discharges within those experimental facilities; 3. The modernization of the ultra-high vacuum system equipped with a cylindrical arc-plasma source, as designed for the deposition of thin superconducting Nb-layers, and the development of arc triggering methods, as well as successful tests performed with the planar arc-plasma source in Rome. (author)