Simultaneous Measurements of Local Axial and Radial Momentum Fluxes near a Radial Wall of a Helicon Source

Axial and radial momentum fluxes near a lateral wall in a helicon plasma source are preliminarily investigated by installing a momentum vector measurement instrument, which has a detector plate mounted on a double-pendulum structure movable in both the axial and radial directions. The result demonstrates the presence of the axial momentum flux transferred to the radial wall, which seems to be delivered by the ions having the axial velocity and lost to the wall. Furthermore, a significantly greater radial momentum flux is lost to the radial wall, implying that the energy loss occurs at the radial wall. The presently shown technique would be useful for identifying the spatial profile of the momentum vector of the plasma.