The magnetohydrodynamical behavior (MHD) of accretion disks is reviewed. A detailed presentation of the fundamental MHD equations appropriate for protostellar disks is given. The combination of a weak (subthermal) magnetic field and Keplerian rotation is unstable to the magnetorotational instability (MRI), if the degree of ionization in the disk is sufficiently high. The MRI produces enhanced a...

We calculate rates of Type I migration of protoplanets in a non-isothermal three-dimensional protoplanetary disk, building upon planet-disk models developed in previous work. We find that including the vertical thickness of the disk results in a decrease in the Type I migration rate by a factor of ∼ 2 from a two-dimensional disk. The vertical temperature variation has only a modest effect on mi...

Formation of the solar system may have been triggered by a stellar wind. From then on, the solar system would have followed a conventional evolutionary path, including the formation of a disk and bipolar jets. The now extinct short-lived radionuclides beryllium-10 and, possibly, manganese-53 that were present in meteorites probably resulted from energetic particle irradiation within the solar s...

A biased Monte Carlo method for the insertion of water in dense clay–water systems is presented. The use of this algorithm results in a considerable increase of the success rate of insertion attempts. It allows us to compute water adsorption isotherms up to high water densities, where the conventional Monte Carlo scheme fails. The isotherms were calculated by a combination of molecular dynamics...

We present a detailed three dimensional magnetohydrodynamic (MHD) simulation describing the inner region of a disk accreting onto a black hole. To avoid the technical complications of general relativity, the dynamics are treated in Newtonian fashion using the pseudo-Newtonian Paczýnski-Wiita potential. The disk evolves due to angular momentum transport that is produced naturally from MHD turbul...

In high power ICRF experiments on the GAMMA 10 tandem mirror, plasmas with a strong temperature anisotropy are produced when the cyclotron resonance layer exists near the midplane of the central cell. Saturation of the diamagnetism is sometimes observed when the heating ICRF power is increased. In the plasmas with the strong temperature anisotropy, Alfvén-ion-cyclotron (AIC) modes are spontaneo...

The ability to modify and control the radial electric field and its radial derivative can lead to direct control of radial transport of plasma in a toroidal device. In the DIII-D tokamak, the injection of deuterium pellets is being investigated as a means of controlling the toroidal rotation velocity and the radial electric field, Er. Solid deuterium cylindrical pellets of 1.8mm and 2.7mm diame...

We study the stability of proto-planetary disks with vertical velocity gradients in their equilibrium rotation rates; such gradients are expected to develop when dust settles into the midplane. Using a linear stability analysis of a simple three-layer model, we show that the onset of instability occurs at a larger value of the Richardson number, and therefore for a thicker layer, when the effec...

Impurity transport coefficients and the penetration efficiencies of intrinsic and injected impurities through the separatrix of diverted Al-cator C-Mod discharges have been measured using x-ray and VUV spec-troscopic diagnostics. The dominant low Z intrinsic impurity in C-Mod is carbon which is found to be present in concentrations of less than 0.5%. Molybdenum, from the plasma facing component...

We created a three-dimensional distribution map of molecular gas throughout the Milky Way Galaxy using the latest CO(J =1–0) survey data cube and rotation curve based on the kinematic distance. The radial distribution of the molecular gas shows a central peak and a second peak around 0.5 R0. The thickness of the molecular disk slightly increases from 48 pc to 160 pc with the galactocentric dist...