Near-Field Propagation of Sub-Nanosecond Electric Pulses into Amorphous Masses

The project, Near-Field Propagation of Sub-Nanosecond Electric Pulses into Amorphous Masses , deals with the propagation of subnanosecond pulsed radiation in the near field region and its use in probing inhomogeneities in dielectrics. It also explores the possibility of changing the physical structure of lossy dielectrics by using very intense pulses. A subnanosecond high voltage pulse generator was constructed, which is able to deliver 150 ps FWHM pulses with 100 ps risetime 10-90. The maximum voltage is 17 kV and the repetition rate is 20 Hz. A prolate-spheroidal reflector antenna focuses subnanosecond pulsed electromagnetic radiation in the near field and its power density distribution has a full-width at half-maximum FWHM width of 32 cm in the axial direction and 10 cm in the lateral direction. The peak electric field inside the lens is 1.4 times of that in air and the spot size is decreased by a factor of 2. A focusing antenna in conjunction with a dielectric lens has been shown to have a resolution of approximately 4 cm. Subnanosecond electric pulses 200 ps at electric field intensities on the order of 20 kVcm cause the death of biological cells and the increased transport across the membrane at much lower exposure times or number of pulses.