The method of and the apparatus for the formation of a high-speed fluid or slurry
jets of a desired geometry are invented. According to the present invention a fluid
or slurry jet is formed by the expelling of a compressed fluid via a slot formed
by two attached plates separated by the insertion. The shape of the slot is determined
by the forms of the plates and the insertion. This shape is also determined by
the deformation of the plates and the insertion by the external forces applied
to the plates, for example by the fasteners connecting the plates.