@article{oai:nifs-repository.repo.nii.ac.jp:00000461,
 author = {YOSHIMURA,  Shinji and OKAMOTO,  Atsushi and OKAMOTO,  Atsushi and TANAKA,  Masayoshi Y. and TANAKA,  Masayoshi Y. and YOSHIMURA,  Shinji},
 journal = {Journal of Plasma and Fusion Research SERIES, Journal of Plasma and Fusion Research SERIES},
 month = {Jan},
 note = {The first experimental observation of a plasma hole structure in an ECR argon plasma is reported. The plasma hole is a cylindrical density cavity, which is formed spontaneously in the center of the plasma. The steep density gradient between the hole plasma and the ambient plasma is sustained by a thin interfacial layer, the width of which is a few ion Larmor radii. Supersonic rotation is found over the large cross-sectional area of Ar plasma hole. The axial flow can also exceed ion sound speed. Spectral measurements revealed that the neutral density profile exhibits a hole structure as well as that in ion density, the diameter of which is much shorter than the mean free path of neutral particles.},
 title = {Observation of Plasma Hole in an ECR Ar Plasma},
 volume = {Vol.6},
 year = {2004}
}