What is the power handling advantage of a pressurized waveguide system?

The power handling advantage of a pressurized waveguide system comes from increasing the dielectric breakdown strength of the gas inside the waveguide by pressurizing it above atmospheric pressure, allowing higher RF voltage swings before electrical breakdown (arcing) occurs. The peak power handling of a waveguide is limited by the electric field strength inside the guide, and breakdown occurs when the field exceeds the dielectric strength of the gas. The breakdown electric field of dry air at sea level is approximately 30 kV/cm (3 MV/m). This corresponds to a peak power limit that depends on the waveguide dimensions. When the waveguide is pressurized: the breakdown field strength increases approximately linearly with absolute pressure: E_breakdown(P) = E_breakdown(P_0) x (P / P_0), where P is the absolute gas pressure and P_0 is atmospheric pressure (101.3 kPa). Since power scales as the square of the electric field: P_max(P) = P_max(P_0) x (P / P_0)². For example: at 2 atm absolute (approximately 15 psig): P_max = 4 x P_max(unpressurized). At 3 atm (approximately 30 psig): P_max = 9 x P_max(unpressurized). This provides a substantial increase in power handling with a relatively simple pressurization system. In addition to power handling: pressurization provides environmental benefits: dry gas (air or nitrogen) prevents moisture from condensing inside the waveguide (which would cause: increased insertion loss, corrosion of the interior surfaces, and reduced breakdown voltage). The positive internal pressure prevents outside air from entering through small gaps or leaks in the waveguide run.