[en] The mission of the CIT device is to study the physics of self-heated fusion plasmas, and to demonstrate the production of substantial amounts of fusion power. In order to achieve this mission with maximum confidence, and minimum cost, CIT is designed as a high-field, compact, copper-alloy-magnet device of modest pulse length. The most appropriate dimensionless parameters to measure extrapolation in confinement physics are ω_cτ_E and nTτ_E/B. CIT is projected to stand midway between JET and the ITER interim conceptual design in these parameters, and so represents a relatively modest step. Nonetheless, because for dimensionlessly similar devices (aB^4/5=const.) nTτ_E is proportional to B, we project CIT to have about the same nTτ_E as ITER, ∼10x that of JET. Our projections for confinement, impurity levels, and profile shapes indicate that CIT should attain Q∼25, with 20 MW of heating power (P_fus=500MW), corresponding to β=3%(=2l/aB). Even given pessimistic assumptions, CIT should achieve its basic mission to determine the confinement physics, operational limits, and α-particle dynamics of self-heated fusion plasmas with α power greater than auxiliary heating power, while producing more than 100 MW of fusion power. In reaching these conditions CIT will also explore heating, fueling, and plasma handling techniques necessary to produce self-heated fusion plasmas, at surface power densities appropriate for economic DT fusion reactors. (author) 5 refs., 2 figs

[en] Nonlinear absorption due to nonlinear Landau damping of lower-hybrid waves is investigated theoretically by analyzing the kinetic wave equations which describe nonlinear Landau damping of electrostatic waves propagating almost perpendicularly to the magnetic field. It is shown that nonlinear ion-cyclotron damping can cause a nonlinear absorption by bulk ions at ω/ω_1h < or approx. 1.2∼1.5, and nonlinear electron Landau damping can cause an efficient nonlinear absorption by bulk electrons at ω/ω_1h < or approx. 1.5∼2. The former nonlinear absorption depends on K perpendicular ρ_i and weakly depends on the electron temperature. The latter depends on the electron temperature strongly. (author)

[en] It has been produced a weakly ionized radiofrequency plasma by electron cyclotron resonance in the Mirror Linear Device LISA of the Universidade Federal Fluminense. The plasma is analyzed both analytically and experimentally. It has been shown that the plasma heating rate is a function of the resonant volume, where two volumes have been considered. The collisional plasma heating process due to the magnetic field modulation has also been studied. (orig.)

[en] A wide variety of spectroscopic techniques exploiting several different atomic processes are used to study the properties of high temperature magnetically confined plasmas. The methods of choice in present experiments use either charge exchange recombination reactions between plasma ions and light neutral atoms injected via high energy neutral beams or fluorescence of beam-injected neutrals excited via collisions with the plasma constituent species. While these techniques allow accurate studies of plasma equilibria, transport properties, and possibly microturbulence in contemporary experiments, the low probability of penetration of neutral beams into dense hot plasmas suggests that extrapolation of these techniques to future fusion ignition experiments may be difficult, and alternative diagnostic techniques based on more classical emission line spectroscopy must also be explored

[en] TORE SUPRA current recently reached 1.9MA exceeding the 1.7MA design value. Experiments are usually carried out with D.C. 4 Tesla toroidal field. Discharges are either leaning on the graphite inner first wall or limited by movable pump limiters located outboard and at the bottom of the vacuum chamber. The plasma major radius can be changed, typically from 2.25m to 2.45m, the maximum minor radius is .8m for either situation. Density is controlled by preprogrammed of feedback gas puffing and by pellet fuelling. Both deuterium and helium have been used, the volume average density was varied from 1.10¹⁹m^-3 to 4.10¹⁹m^-3. A 1.MA D₂ typical discharge with density 2.10¹⁹ m^-3 has ion and electron central energy of 1.8keV and 2.2keV respectively. Energy lifetime from diamagnetic measurements is .18s in accordance with integration of local energy content. (author) 6 refs., 6 figs

[en] Langmuir probe data obtained from about 290 Ohmic discharges in the Frascati Tokamak (FT) have been analysed in the following ranges of macroscopic plasma parameters: line averaged plasma density n-bar_e=2.5x10¹³ to 2.7x10¹⁴cm^-3, plasma current I_p=230-450 kA, toroidal magnetic field B_T=6T and 8T. The principal parameters of the scrape-off layer (SOL) plasma, i.e. the density and the temperature at the limiter radius, n_eL and T_eL, respectively, and their e-folding lengths λ_n and λ_T have been obtained and correlated with those of the main plasma. The scaling laws for n_eL and T_eL as a function of the macroscopic plasma parameters are explained only partially with the existing simple diffusion models, which cannot account for the experimentally observed dependence of n_eL on the safety factor q_L. The empirical laws are n_eL=3.96x10^-2n-bar_e^1.38q_L and T_eL=6.5(I_p/q_L)^2/3n-bar_e^-0.75, where n-bar_e and n_eL are in units of 10¹³cm^-3, T_e is in eV and I_p in kA. For λ_n, the scaling λ_n=1.05n-bar_e^-0.25cm holds, with the same units. No reliable law is derived for λ_T, but the approximate relationship λ_T approx. 2.5-4λ_n always holds true. The fluctuations in the SOL and their role in determining the perpendicular particle diffusion and, hence, λ_n are discussed. (author). 17 refs, 8 figs

[en] In a conventional tokamak type thermonuclear device, occurrence of kink instability causing flex-like deviation in the toroidal direction can not be detected. In view of the above, a detector for the positional shape of a plasma cross section is disposed at one position in the toroidal direction of the device, for example, at φ = 0deg to control the plasma position. Then, a second detector is disposed at a position φ = 90deg. The output signals from the two detectors are compared and, if the difference exceeds a limit value, plasma current is decayed. If the kink instability appears in the plasmas, the plasma position varies sinusoidally in accordance with the increase of φ. Accordingly, by disposing the second detector at φ = 90deg, if the kink instability at mode n = 1 appears, the deviation of the plasma cross sectional position can be detected at its maximum value. (N.H.)

[en] The ideal rectangular axial structure of the eigenfunction of the curvature driven trapped particle mode, localized in the central cell of a tandem mirror is critically examined and revised. The search for a physical damping mechanism which can truncate the short wavelength part of the spectrum of the ideal eigenfunction has led to the halo coupling of the trapped particle mode. The radial coupling of the trapped particle mode to the halo plasma can excite acoustic modes which are strongly damped at short wavelengths. This mechanism can easily smooth out the ideal rectangular structure. Approximate results indicate a significant departure from the ideal rectangular structure and a corresponding reduction of the growth rate. (author). 6 refs, 2 figs

[en] Two MHD models for instability, viz., the Shafranov's resistive free-boundary and resistive fixed-boundary step models have been revisited. In the former, a constant longitudinal current density passes through a cylindrical column of a resistive plasma of radius a separated by vacuum from a perfectly conducting wall at a radius b; in the latter, the current density has the same radial profile but the plasma fills the whole cylinder up to the conducting wall. For the former, the explicit dependence of resistivity η on the maximum normalized growth rate Γ_max is exhibited showing a stabilizing effect on kinks. A fact that is overlooked by some authors is also pointed out here in the form of a correction of the original growth rate γ_max. For the latter, a special code set up to solve the (stiff) system of differential equations for instability in the region a≤r≤b, together with a set of jump conditions at the current channel radius a, yield no solution satisfying the appropriate boundary conditions at the wall. (orig.)

[en] The present paper reformulates the neoclassical theory of general toroidal equilibria. The relevant geometrical parameters are identified and it is shown how the reduction of Pfirsch-Schlueter currents affects neoclassical transport and bootstrap effects. The influence of turbulent electromagnetic fluctuations is also discussed. Since a toroidal loop voltage is included, the theory is valid for all toroidal systems. (author)