Conductivity Induced by High-Field Terahertz Waves in Dielectric Material

Area of Science:

• Physics
• Plasma Physics
• Materials Science

Background:

• Relativistic electron beams in dielectric-lined waveguides generate high-power terahertz (THz) radiation via the wakefield mechanism.
• Previous work demonstrated high-power, narrow-band THz radiation generation exceeding 2 GV/m.
• Such intense THz fields are crucial for particle acceleration and advanced spectroscopy.

Purpose of the Study:

• To investigate the physical mechanisms behind strong field-induced damping of THz radiation in silicon dioxide (SiO2).
• To characterize the onset and nature of wave attenuation at gigavolt-per-meter field strengths.
• To understand the role of dielectric conductivity changes and latching mechanisms in THz wave propagation.

Main Methods:

• Utilizing intense, subpicosecond, relativistic electron beams traversing a dielectric-lined waveguide.
• Employing detailed measurements to analyze THz radiation generation and propagation.
• Observing wave attenuation in SiO2 starting around 850 MV/m.

Main Results:

• Measured THz field amplitudes exceeding 2 GV/m were achieved.
• A strong damping effect in SiO2 was observed for fields approaching the GV/m level.
• Wave attenuation onset near 850 MV/m is linked to reversible changes in dielectric conductivity.
• A distinctive latching mechanism contributing to the damping was identified.

Conclusions:

• The study clarifies the physical mechanisms responsible for strong field-induced damping of THz radiation in SiO2.
• The observed damping is consistent with field-dependent conductivity changes in the dielectric material.
• The reversible nature of the latching mechanism offers potential for controlling high-power THz wave propagation.