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Helicon plasma sources are very useful in many aspects and are applicable to many fields across science and technology, as they can supply high-density (\sim10^13~cm^-3) plasmas with a broad range of external operating parameters. In this paper, developed, featured sources with various sizes are characterized along with discussions on their particle production efficiency. This paper aims to develop systems that can realize schemes with completely electrodeless plasma production and acceleration. This is expected to mitigate the existing problems of the finite lifetimes inherent in electric plasma propulsion tools. Experimental and theoretical approaches that implement such schemes are presented. [ABSTRACT FROM PUBLISHER]

We report on the development of unique, high-density helicon plasma sources and describe their applications. Characterization of one of the largest helicon plasma sources yet constructed is made. Scalings of the particle production efficiency are derived from various plasma production devices in open literature and our own data from long and short cylinder devices, i.e., high and low values of the aspect ratio A (the ratio of the axial length to the diameter), considering the power balance in the framework of a simple diffusion model. A high plasma production efficiency is demonstrated, and we clarify the structures of the excited waves in the low A region down to 0.075 (the large device diameter of 73.8 cm with the axial length as short as 5.5 cm). We describe the application to plasma propulsion using a new concept that employs no electrodes. A very small diameter (2.5 cm) helicon plasma with 1013 cm-3 density is produced, and the preliminary results of electromagnetic plasma acceleration are briefly described. [ABSTRACT FROM AUTHOR]

A high-density helicon plasma source with very large volume, 75 cm in diameter and 486 cm in axial length, has been developed, and its characteristics have been investigated. Furthermore, the radial density profile control has been successfully demonstrated by utilizing two techniques: (1) by changing the magnetic field configurations near the antenna and (2) by changing the antenna radiation-field patterns. Using two types of large-diameter spiral antennae, plasma with density exceeding 1012 cm-3 has been produced with several hundreds of watts of radio frequency power. By changing the magnetic field configuration near the antenna, the threshold power and the degree of the density change in a density jump can be varied. The electron density reaches the maximum away from the antenna; then decays weakly along the axial direction. [ABSTRACT FROM AUTHOR]

We have developed a very large volume, high-density helicon plasma source, 75 cm in diameter and 486 cm in axial length; full width at half maximum of the plasma density is up to ∼42 cm with good plasma uniformity along the z axis. By the use of a spiral antenna located just outside the end of the vacuum chamber through a quartz-glass window, plasma can be initiated with a very low value of radio frequency (rf) power (<1 W), and an electron density of more than 1012 cm-3 is successfully produced with less than several hundred Watt; achieving excellent discharge efficiency. It is possible to control the radial density profile in this device by changing the magnetic field configurations near the antenna and/or the antenna radiation-field patterns. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Full penetration of RF electric fields into magnetized plasmas is expected in order to realize the Lissajous helicon plasma accelerator (LHPA). We study the electric field penetration in bulk plasma in one-dimensional electrostatic approximation using two analytical models: the matrix sheath model and the vacuum gap model. An identical formula for the electric field is obtained from the models. The formula is benchmarked by particle-in-cell (PIC) simulations. The full penetration of the electric field is realized when the relation (q ≪0.01) is satisfied, where q is the measure of the degree of the shielding effect due to plasma density and electron magnetization. [ABSTRACT FROM AUTHOR]