The electromagnetic longitudinal wave in vacuum is the wave of compression/decompression in the local curvature of space (or in the local rate of flow of time). It is a gravitational wave. The  application of such waves for cold fusion stimulation or for antigravity are required for learning of its biological aspect at first.

The technology is the next. According to Dr. K.P. Butusov, St.-Petersburg, the power of an electric condenser that is transformed into longitudinal wave power when the volume of the condenser is decreased is equal to:

where W is energy and V is volume.

The form of the electric condenser is not important in this case. The sphere is an example of condenser that creates longitudinal waves in all directions when its size of the charged sphere is changed (decreased).

To create a certain direction of longitudinal waves emission is possible [as shown] in next simple system. Fig. 1 shows the cylindrical charged condenser that has variable length in one side.

                    
 Note that the power of longitudinal waves is connected with the ratio dV/dt (Velocity of change of volume) since the changing volumetric density of energy is the cause of this wave. Also note that when the sphere or cylinder charged condenser is compressed, it is necessary to disconnect the primary source of high voltage potential, or it is necessary to use diode in charging circuit.