Speaker
Shunjiro Shinohara
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/I1.402.pdf
Characteristics of Various High-Density Helicon Sources
and their Application to Electrodeless Plasma Thruster
Shunjiro Shinohara
Tokyo University of Agriculture and Technology, Tokyo 184-8588, Japan
Because of high-density (~1013 cm-3) and low electron temperature (from a few to
several eV) available with a broad range of external operating parameters, helicon plasma
sources [1,2], using an rf frequency range, are very useful. Various kinds of the sources have
been developed and characterized by us to control plasmas as required: e.g., very large- [3,4]
(up to 74 cm in diameter with an axial length of 486 cm) or very small-area [5,6] (down to
0.1-0.3 cm in diameter) sources can be found. Particle production efficiency in a wide range
of plasma size showed an excellent performance [4], close to a classical diffusion coefficient.
High-beta (~ 1) plasma can be easily achieved, showing an importance of neutrals effect [7].
Therefore, these sources can be expected to be utilized in vast areas from fundamental to
application fields. Applying these sources to a space propulsion system with an advanced
concept of an electrodeless condition (no direct contact between a plasma and
electrodes/antennas) [4,6] has been executed, due to a longer life operation expected.
Here, we will overview our studies on various-sized, helicon plasma sources and their
application to the electrodeless thrusters under the Helicon Electrodeless Advanced Thruster
(HEAT) project [4,6]: Characteristics of very large or small (diameter) sources, and plasma
thrust performance [6,8]. Here, a broad range of excitation frequency, 7-435 MHz, was used
for optimization of plasma sources. In addition, some trials of electrodeless, additional
acceleration methods are introduced, such as Rotating Magnetic Field (RMF) and m = 0 half
cycle schemes [6], emphasizing the importance of some diagnostics.
[1] R. W. Boswell, Phys. Lett. 33A, 457 (1970).
[2] S. Shinohara, Adv. Phys.:X 3, 185 (2017) (Review Paper), and references therein.
[3] S. Shinohara and T. Tanikawa, Rev. Sci. Insturm. 75, 1941 (2004).
[4] S. Shinohara, T. Hada, T. Motomuta, K. Tanaka, T. Tanikawa, K. Toki, Y. Tanaka, and K. P. Shamrai,
Phys. Plasmas. 16, 057108 (2009).
[5] D. Kuwahara, A. Mishio, T. Nakagawa, and S. Shinohara, Rev. Sci. Instrum. 84, 103502 (2013).
[6] S. Shinohara, H. Nishida, T. Tanikawa, T. Hada, I. Funaki, and K. P. Shamrai, IEEE Trans. Plasma Sci. 42,
1245 (2014).
[7] S. Shinohara, D. Kuwahara, K. Yano, and A. Fruchtman, Phys. Plasmas 23, 122108 (2016).
[8] D. Kuwahara, S. Shinohara, and K. Yano, J. Propul. Power 33, 420 (2017).
