# Plasma and Fusion Research

## Volume 3, S1011 (2008)

# Regular Articles

- Department of Electronic Engineering, Tohoku University, Sendai 980-8579, Japan
- 1)
- National Institute for Fusion Science, Toki 509-5292, Japan

### Abstract

Plasma flow velocity shears parallel and perpendicular to magnetic field lines are independently controlled and superimposed by a modified plasma-synthesis method with concentrically three-segmented electron and ion emitters. The fluctuation amplitude of a drift wave with an azimuthal mode number m = 3 is observed to increase with increasing parallel shear strength in the absence of a perpendicular shear. When the perpendicular shear is superimposed on the parallel shear, the drift wave with m = 3 is found to transform into that with m = 2. Furthermore, the parallel shear strength required for excitation of the drift wave increases with a decrease in the azimuthal mode number. Based on these results, superposition of the parallel and perpendicular shears can affect characteristics of the drift wave through variation of the azimuthal mode number. These phenomena can be verified by theoretical calculations of the growth rate of the drift wave using an eigenmode analysis.

### Keywords

plasma flow velocity shear, drift wave, azimuthal mode number, plasma-synthesis method

### Full Text

### References

- [1] E. Agrimson, N. D'Angelo and R.L. Merlino, Phys. Rev. Lett. 86, 5282 (2001).
- [2] C. Teodorescu, E.W. Reynolds and M.E. Koepke, Phys. Rev. Lett. 88, 185003 (2002).
- [3] C. Teodorescu, E.W. Reynolds and M.E. Koepke, Phys. Rev. Lett. 89, 105001 (2002).
- [4] E. Agrimson, S.-H. Kim, N. D'Angelo and R.L. Merlino, Phys. Plasmas 10, 3850 (2003).
- [5] T. Kaneko, H. Tsunoyama and R. Hatakeyama, Phys. Rev. Lett. 90, 125001 (2003).
- [6] T. Kaneko, E.W. Reynolds, R. Hatakeyama, and M.E. Koepke, Phys. Plasmas 12, 102106 (2005).
- [7] R. Hatakeyama and T. Kaneko, Phys. Scripta T107, 200 (2004).
- [8] T. Kaneko, K. Hayashi, R. Ichiki and R. Hatakeyama, Trans. Fusion Sci. Technol. 51, 103 (2007).
- [9] M.E. Koepke and E.W. Reynolds, Plasma Phys. Control. Fusion 49, A145 (2007).
- [10] T. Kaneko, Y. Odaka, E. Tada and R. Hatakeyama, Rev. Sci. Instrum. 73, 4218 (2002).
- [11] R. Hatakeyama, M. Oertl, E. Märk and R. Schrittwieser, Phys. Fluids 23, 1774 (1980).
- [12] G. Ganguli, M. J. Keskinen, H. Romero, R. Heelis, T. Moore and C. Pollock, J. Geophys. Res. 99, 8873 (1994).
- [13] A. Ito and A. Hirose, Phys. Plasmas 11, 23 (2004).
- [14] V.V. Gavrishchaka, S.B. Ganguli, G.I. Ganguli, Phys. Rev. Lett. 80, 728 (1998).

This paper may be cited as follows:

Toshiro KANEKO, Shuichi TAMURA, Atsushi ITO and Rikizo HATAKEYAMA, Plasma Fusion Res. 3, S1011 (2008).