Efficiency of flux build-up with high repetitive Spheromak injection

A spheromak plasma generated by magnetic coaxial plasma gun is able to be accelerated easily by Lorentz force due to self magnetic field and discharge current. Then the plasmoid is expected as a magnetic helicity and particle injector for nuclear fusion core. To supply significant amount of helicity and particles with minimum disturbance on a target plasma, a plasmoid has to be generated with higher repetitive ratio of 50 kHz. Currently we are focusing on to estimate the efficiency of helicity injection in a high repetitive operatio case. In a preliminary experiments with pyrex discharge tube with guide magnetic field, increased decay time of poloidal magnetic flux and emission of line spectrum of He?U have been observed. To investigate generation efficiency of magnetic flux in more detail, metal flux conserver was installed and detailed internal probe measurements have been conducted.