The use of three types of antenna was attempted for the frequency shift probe measurement: (a) type 1 of double opened loops, (b) type 2 of double zigzag wires, and (c) type 3 forceps-shaped wires.
Schematic of the top view inside the chamber indicating the positions of the Langmuir probe tip and the type 1 antenna, which is drawn by superposing the tip and the antenna.
Typical characteristics of the electron current, Ie , sampled by a conventional Langmuir probe at 10 Pa in a plasma without dust particles. Two lines were found in extrapolation.
(a) The electron temperature and (b) plasma density as functions of pressure at constant rf set points of 800, 1600, 2400, and 3200 RFS, measured by a conventional Langmuir probe, the tip of which was 20 mm above the bottom electrode and 25 mm far from the center in a radial direction.
The reflection of power, namely so-called return loss, as measured with a type 1 antenna and a network analyzer with 1 mW output power in a vacuum and plasmas at 27 Pa. Each curve corresponds to each parameter of the rf set point from 0 (without plasma) to 3200 RFS.
The electron densities as functions of the rf set point measured with the Langmuir and frequency shift probes at 27 Pa. The Langmuir probe tip was set the same as in Fig. 4. The type 1 antenna was set 20mm above the bottom electrode, and rotated from θ = 0 to 67.5° to measure at the edge as shown in Fig. 2.
The spatial distribution profiles of electron density measured with a type 1 antenna at 27 Pa in plasmas without dust particles. (a) Longitudinal profiles between electrodes, represented by a function of height from the bottom electrode at a constant rf set point from 400 to 3200 RFS. (b) Angular profiles of electron density, measured by rotating the antenna 15 mm above the bottom electrode as represented by the rotating angle function as defined in Fig. 2.
The axial distribution profiles of electron density measured with the type 2 antenna located above the center of the electrode changing the rf set point from 200 to 2800 RFS and pressure from 10 to 40 Pa.
The electron density as a function of the dust particle density: measured with a type 1 antenna, which was located near the edge of the dust cloud. Particles of 2.55 μm were injected into the plasma generated at power of 400 RFS and pressure of 40 Pa.
The longitudinal distribution profiles of electron density measured in the plasmas with and without dust particles. Particles of 2.55 μm were injected into the plasma generated at power of 400 RFS and pressure of 27 Pa.
The values of electron densities calculated with the electron-neutral collision effect for specific electron temperatures of 1 and 2 eV. The dotted line indicates the value of 108 cm−3 derived in the collision-less calculation, assumed to be measured by an antenna with f0 of 750.000 MHz and fr of 750.355 MHz.
The spatial distributions of dust particle observed in parabolic flight experiments, represented by dots plotted in the coordinates of the radius (distance from the axis center) and height from the bottom electrode: (a) at 220 RFS of power and 26 Pa of pressure under gravity (1 G), (b) at the power and pressure under microgravity (μG), (c) at 1000 RFS and 54 Pa under 1 G, and (d) at the power and pressure under microgravity.
The axial distribution profiles of electron density, as measured with the type 2 antenna under conditions corresponding to the parabolic flight experiments (Fig. 12).
The effective current values on the top and bottom electrodes, and gravity as variations on flight time at 220 RFS of power and 26 Pa of pressure in the parabolic flight.
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