抄録
Recently, magnetic stimulations of living body by using time-varying magnetic field have been investigated with respect to stimulator and its effect. The authors have been developing the more focal magnetic stimulator which is effective for stimulating tissue of human body. In this developing process, the density distribution of the eddy current induced in saline tank by magnetic stimulator coils has been measured with a current probe in order to examine the effectiveness of the coils. The probe is made of ultra-mini coaxial cable and detects the eddy current signal of 20kHz sinusoidal wave with the current density resolution of about 0.2μA/mm2 and with the half angular resolution of about 40 degrees. The probe is set in the current stream at a measuring point, and the picked-up current as the current density signal is transmitted to a measuring instrument with inductive interference suppressed. The measured values at the lattice points on a horizontal plane make up the arrow map of the current distribution.
Experiments are made by combining several coils and tanks. The experiment in the semi-infinite volume shows that the measured distribution agrees well with the computed distribution. The other experiments in the tank simulating human limb show the difference of concentration due to the effect of boundary.
