@article{oai:iwate-u.repo.nii.ac.jp:00009942,
 author = {Takahashi, K and Fujiwara, T},
 issue = {6},
 journal = {Applied Physics Letters},
 month = {Feb},
 note = {The spatial distribution of an ion beam created in a magnetically expanding plasma using permanent magnets is experimentally investigated for 0.35 and 1 mTorr, where the magnetic-field strength is about 100 G in the plasma source and is decreasing into a few gauss in the diffusion chamber. The beam profile for 0.35 mTorr is weakly divergent. On the other hand, the strongly diverging beam is detected for 1 mTorr. The results are discussed from the viewpoint of the plasma-potential structures and imply the beam divergence caused by the radial electric fields in the ion acceleration region and the diffusion chamber.},
 pages = {061502-1--061502-3},
 title = {Observation of weakly and strongly diverging ion beams in a magnetically expanding plasma},
 volume = {94},
 year = {2009}
}