Krieger wave
A Krieger wave is a powerful type of energy wave. It had the ability to melt duranium and had an energy signature similar to that of a phaser beam. These waves could be reflected off of transporter beams.

Dr. Nel Apgar, in the 2360s, developed a procedure that produced these waves using a device which converted collimated lambda field pulses through a series of mirrors and reflective coils.

The  was interested in Dr. Apgar's technology for a potential energy source. However, Dr. Apgar denied having developed them because he had become motivated by profit, and was developing the technology to be used as a weapon instead. Fearing the Federation was suspicious of him, Apgar had intended to kill Commander Will Riker with a Krieger wave, but, instead, the wave reflected off the transporter beam and hit the station's reactor. 

During the investigation into the explosion, the  accidentally experienced these waves since they had recreated Apgar's converter on its holodeck using his exact design. ()

de:Kriegerwelle
Energy