Experimental study on a quasi-optical mode converter for a 0.42THz TE17,4 mode gyrotron

A quasi-optical mode converter (QOMC) for a 0.42 THz, TE_17,4 mode gyrotron is designed and tested. The numerical results show that the scalar fundamental Gaussian mode content of the wave beam at the output window is about 98.1%, the vector content is about 79.1%. The experiment result shows that a well-focused Gaussian-like beam with 95.2% scalar Gaussian mode content has been obtained by using an infrared video camera indirectly. The measured results agree well with the theoretical predictions.