[en] The paper presents the experimental examination of a law-hybrid plasma were excited by beatings of two high-frequency electron-cyclotron waves. Resonance nature of excitation of such a wave by the value of magnetic field, dynamics of rise and dependence of wave intensity by plasma density are shown. 14 refs., 5 figs

[en] The injection of high power electrostatic waves into a plasma causes ponderomotive forces to arise. Their action primarily gives rise to a plasma density decrease in front of the launching system and subsequently it affects both the wave injection and propagations. Several experimental and theoretical studies on ponderomotive effects caused by injection of lower hybrid waves (LHW) in linear devices can be found in literature and they reveal a density decrease along the magnetic field whereas no detailed studies on the ponderomotive effects of electrostatic waves in the direction perpendicular to the magnetic field were made up to now. This work concerns an experimental study of the variations of the electron density profiles in a direction perpendicular to the magnetic field occurring in a toroidal plasma when a high power electrostatic wave in the range of the ion cyclotron frequency is launched. As part thereof an analysis of the modifications of the envelope of the electrostatic wave as well as of the coupling properties of the antenna system to the plasma has been performed. By means of this analysis, the presence of density depletions at the edge of the plasma during the application of a high power signal has been revealed. In addition the strong edge electron heating observed in our experiments is presented. The experiment has been carried out on a weakly ionized steady-state hydrogen plasma with major radius R = 40 cm, minor radius r = 8 cm, toroidal magnetic field intensity B_o ∼ 2 kG and vertical magnetic field intensity B perpendicular ∼ 3G. The plasma density is typically 10⁸ cm^-3 at the edge and 10¹⁰ cm^-3 on the axis of the torus

[en] A new mode of operation using only the second stage of the LBL ECR has been developed. This single stage mode produces charge states and currents equal to or better than the traditional two stage operation of the LBL ECR for a variety of gases such as nitrogen, oxygen, and argon. The critical parameter for this mode appears to be conditioning the plasma chamber walls with a coating of SiO₂. Various models to explain this effect will be discussed along with implications for ECR ion source design. A new Advanced ECR ion source which will operate at 14 GHz is being designed for the 88-Inch Cyclotron. Construction is scheduled to begin in the fall of 1988 and test operation should begin in the fall of 1989. The design includes hollow core copper wire solenoids, iron yoke, a Nd-Fe-B sextupole, radial pumping, and access to the plasma chamber. 8 refs., 4 figs., 1 tab

No abstract available

[en] One-dimensional diffusion is considered for a system in which the diffusion coefficient D has a rapid oscillation in the spatial variable as well as a slow variation. For long times, the distribution function evolves diffusively with an effective diffusion coefficient given by averaging 1/D

[en] Despite the high level of performance today achieved, launching rf power in ECR ion sources (ECRIS) still remains very empirical, and the exact description of waves absorbed in ECRIS is also a major unknown. The present article simply tries to give some answer to the following questions: which rf wave has to be launched, and how to launch this wave in order to efficiently heat the plasma electrons and optimize the rf power absorption as well as the source performance? Therefore two main aspects of this problem are considered: (i) on one hand the rf waves that can exist and propagate in ECRIS, either plasma waves or electromagnetic eigenmodes, (ii) on the other hand the rf coupling systems to develop accordingly. Emphasis is given to the latter topics. (author)

No abstract available

[en] The effects of mode conversion theory on emission have led to some surprising results. The classical expressions were originally derived from models which did not include mode conversion or its attendant reflection. When mode conversion was included, the first surprise was that the transmission coefficient is totally independent of absorption and due exclusively to tunneling. The other surprise is that the observed emission arises from two distinct sources, one direct, and one from an indirect Bernstein wave source which is partially converted in the cyclotron layer to outgoing electromagnetic waves, with the net result that mode conversion cancels out for the electron case. The only corrections to electron cyclotron emission are then due to reflection effects, and these have been shown to be small for laboratory plasmas, leading to the validation of the classical formula, but via an entirely new paradigm in its interpretation. This paper includes a summary of the absorption process for electron cyclotron harmonics, and reviews the emission physics, including both potential error estimates and a discussion of the spatial emission source distribution

[en] Plasma chamber in an ECR device is an important component. It has vacuum of the order of 10^-7 mbar and it acts as an empty resonant multi-mode cavity for the launched EM microwave. The microwave selectively heats the electrons through ECR on a particular surface in the chamber. Results of investigations on electric field of the EM wave transferring energy to the electrons inside it are given

[en] Experimental results for electron cyclotron resonance in a longitudinally magnetized plasma waveguide (LMG plasma column) are shown as a function of em wave polarization launched into the plasma. The results show the importance of the mentioned polarizations. The plasma electronic density which supply the power transfer effectiveness has a strong dependence with polarization. On the other hand, a slip could be noticed in the RHCP wave (optimum polarization) towards a right hand elliptically polarized wave depending on the work pressure which has a direct relationship with the collisional character of the plasma. (author)