Observation of Bifurcation Property of Radial Electric Field Using a Heavy Ion Beam Probe / by Osakabe, M., author, Nomura, I., author, Ida, K., author, Okamura, S., author, Toi, K., author, Kado, S., author, Akiyama, R., author, Shimizu, A., author, Takahashi, C., author, Kojima, M., author, Matsuoka, K., author, Hamada, Y., author, Fujiwara, M., author, Fujisawa, A., author, Iguchi, H., author, Minami, T., author, Yoshimura, Y., author, Sanuki, H., author, Itoh, K., author, Isobe, M., author, Nishimura, S., author, Tanaka, K., author, IAEA Fusion Energy Conference (18th : 2000 : Sorrento, Italy)