@techreport{oai:nifs-repository.repo.nii.ac.jp:00010382,
 author = {"Wakabayashi,  H. and Himura,  H. and Isobe,  M. and Okamura,  S. and Matsuoka,  K."},
 month = {Sep},
 note = {"It is observed, for the first time, that the space potential is non-uniform on magnetic surfaces in nonneutral helical plasmas. Electron plasmas are generated in a stellarator magnetic field by injection from an electron gun. Electrons are launched out with the acceleration voltage (Vacc) from 300V to 1kV. The potential non-uniformity is almost proportional to Vacc. Experimental errors such as missalignment of the measurement probe and the perturbing effect of probe insertion are carefully checked, and confirmed not to be the reason of the observed potential variation."},
 title = {Observation of Non-Uniformity of Space Potential on Magnetic Surfaces in Helical Nonneutral Plasmas},
 year = {2005}
}