Measurements of The Sheath Potential in Low Density Plasmas

摘要: The authors have measured the sheath potential around a probe in range of different plasma conditions UMIST quadrupole GOLUX and related experiment which expands freely to supersonic velocity. In latter case, agrees well with an appropriately modified form usual expression for field-free plasma, both hydrogen argon plasmas. GOLUX, however, is found be significantly less than accepted value, even when magnetic field taken into account. For slow-moving outer part confining field, they present theoretical experimental results showing that reduction due truncation electron velocity distribution as drains electrons from closed flux-tube faster can replaced. central hot this explanation cannot apply. Here moving at about sonic speed effects are weak. Nevertheless those experiment.