A 57-pin langmuir probe array for two-dimensional diagnosis in the toroidal KT-5D steady-state plasma

In this article, the design idea of a 57-pin Langmuir probe array is presented, together with some experimental results. The manufacture technique of the probe array is discussed. Two-dimensional distributions of the plasma density, the floating potential and their fluctuations in the poloidal cross section are obtained. The blobs, which move radially and poloidally, cause great particle and energy transport. The charge neutralization by the poloidal movement of particles greatly decreases the vertical electric field in the helimak plasma. This leads to a confinement time which is two orders of magnitude larger than the theoretical prediction.