Peculiarities of 2 mm Orotron Operation on Second Space Harmonic

It is shown that the output power on the second space harmonic may be comparable with that on the first space harmonic at one-wave DRR regime. The possibility of the orotron OPS period increasing and tooth grating width increasing even operating only on the second space harmonic is demonstrated. The 3 times tooth grating width increase will allow to improve the hardness of small size OPS. Thus it is shown that the low- voltage orotrons may be effectives in THz wavelength range operating at one-wave DRR regime when their OPS parameters are optimized for high-order space harmonic operation. The work was partly fulfilled at the DPhS RAS "The radio physic problems" support, the "terahertz range development" division.