The use of electric motors or generators for aircraft application requires fewer prime movers and auxiliary equipment than conventional propulsion systems. Thus, the performance in terms of efficiency, reliability is improved. However, the dynamic behaviour of an aircraft required motor which transmit high torque on the propellers. The challenge is to develop an axial-field superconducting motor or a generator with high power density, up to 20 kW/kg The inductor is composed of several YBCO bulks located inside a YBCO solenoid. The solenoid is fed by a direct current and produce a magnetic field in the axial direction. The diamagnetic behaviour of a superconducting bulk cooled under zero-field is used to obtain a variation of the magnetic flux density in the air-gap. The YBCO bulks is one of the critical parts of this electrical machine. It is therefore important to know their characteristic. In this paper, we present experimental tests for the YBCO bulk at several temperature in order to evaluate their performance in terms of screening.