Abstract: A data reader may have an resonant tunnel structure disposed between first and second magnetic structures. The resonant tunnel structure can be configured with a spacer layer disposed between first and second barrier layers. The first barrier layer can have a first thickness that is smaller than a second thickness of the second barrier layers with the thicknesses each measured along a common plane to provide resonant tunneling for the data reader.

Abstract: A data reader may have an resonant tunnel structure disposed between first and second magnetic structures. The resonant tunnel structure can be configured with a spacer layer disposed between first and second barrier layers. The first barrier layer can have a first thickness that is smaller than a second thickness of the second barrier layers with the thicknesses each measured along a common plane to provide resonant tunneling for the data reader.

Abstract: A method for loosening and removing sludge and debris from the vessel of a heat exchanger, such as the secondary side of a nuclear steam generator, is disclosed herein. The method generally comprises the steps of providing a sufficient volume of a liquid, such as water, into the steam generator so that the lower portion which includes the tubesheet is submerged, and then generating a succession of pressure pulses within the water from one or more pressure pulse generators wherein each pressure pulse creates shock waves that exert momentary forces throughout the submerged portion of the generator of a magnitude sufficient to loosen the sludge and debris, but safely below the yield and fatigue limits of the heat exchanger tubes and other components within the generator. The pressure pulses commence as soon as a sufficient amount of water is introduced into the steam generator to submerge the tubesheet, and continue all the way through the draining of the steam generator.

Abstract: A method for loosening and removing sludge and debris from the vessel of a heat exchanger, such as the secondary side of a nuclear steam generator, is disclosed herein. The method generally comprises the steps of providing a sufficient volume of a liquid, such as water, into the steam generator so that the lower portion which includes the tubesheet is submerged, and then generating a succession of pressure pulses within the water from one or more pressure pulse generators wherein each pressure pulse creates shock waves that exert momentary forces throughout the submerged portion of the generator of a magnitude sufficient to loosen the sludge and debris, but safely below the yield and fatigue limits of the heat exchanger tubes and other components within the generator. The pressure pulses commence as soon as a sufficient amount of water is introduced into the steam generator to submerge the tubesheet, and continue all the way through the draining of the steam generator.