A well tool (10) for use in a well pipe comprises a housing (11) and a pulse generator (14) provided within the housing (11). The pulse generator (14) comprises an inductor (Ls), and a power supply device (HV, c) for supplying electrical power to the inductor (L) and thereby providing that an electromagnetic pulse is generated, in such a way that the electromagnetic pulse is providing physical vibrations in the well pipe. A cross sectional gap area (Agap) of an annular gap between a median of the inductor (Ls) and an inner surface of the well pipe is substantially equal to an inner cross sectional area (Ainner) of the inductor (Ls) up to the median diameter (d) of the inductor.
