For the numerical simulation of electron cyclotron resonance plasma production, a two-dimensional model that describes wave propagation and plasma transport is developed. The modeling code calculates profiles of electromagnetic wave fields, power absorption of electrons, and temporal evolution of plasma densities in a bounded, inhomogeneous, cylindrical system. The calculation of the plasma production in a mirror magnetic field shows that the plasma production property is very sensitive to the antenna location.

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High-energy tail formations due to the monochromatic wave in a magnetized plasma are studied numerically and analytically. By calculating the phase space trajectories of 10 000 particles, initially Maxwell-velocity-distributed, in the presence of a uniform magnetic field and a sinusoidal wave traveling closely in the perpendicular direction with the frequency of cyclotron harmonics, some properties of particle acceleration are clarified. The acceleration mechanism can be described by a modification of trapping theory and two types of stochastic acceleration. The behavior of the high-energy tail formation depends on the magnitude of ω/Ω. For small ω/Ω (ω/Ω≲10), the cyclotron harmonics resonance is very important. The ratio of the perpendicular wavelength to the average Larmor radius and the wave amplitude play an important role in determining the ratio of tail to the bulk portion.

Introduction:We aim to elucidate the effect of spatial resolution of three-dimensional cine phase contrast magnetic resonance (3D cine PC MR) imaging on the accuracy of the blood flow analysis, and examine the optimal setting for spatial resolution using flow phantoms.Materials and Methods:The flow phantom has five types of acrylic pipes that represent human blood vessels (inner diameters: 15, 12, 9, 6, and 3 mm). The pipes were fixed with 1% agarose containing 0.025 mol/L gadolinium contrast agent. A blood-mimicking fluid with human blood property values was circulated through the pipes at a steady flow. Magnetic resonance (MR) images (three-directional phase images with speed information and magnitude images for information of shape) were acquired using the 3-Tesla MR system and receiving coil. Temporal changes in spatially-averaged velocity and maximum velocity were calculated using hemodynamic analysis software. We calculated the error rates of the flow velocities based on the volume flow rates measured with a flowmeter and examined measurement accuracy.Results:When the acrylic pipe was the size of the thoracicoabdominal or cervical artery and the ratio of pixel size for the pipe was set at 30% or lower, spatially-averaged velocity measurements were highly accurate. When the pixel size ratio was set at 10% or lower, maximum velocity could be measured with high accuracy. It was difficult to accurately measure maximum velocity of the 3-mm pipe, which was the size of an intracranial major artery, but the error for spatially-averaged velocity was 20% or less.Conclusions:Flow velocity measurement accuracy of 3D cine PC MR imaging for pipes with inner sizes equivalent to vessels in the cervical and thoracicoabdominal arteries is good. The flow velocity accuracy for the pipe with a 3-mm-diameter that is equivalent to major intracranial arteries is poor for maximum velocity, but it is relatively good for spatially-averaged velocity.