Gyrotron FU II for a radiation source of THz ESR spectroscopy with a high field pulse magnet

For ESR spectroscopy covering sub THz to THz region, we have developed a frequency-step tunable Gyrotron FU II as a radiation source. A pulse magnet is used for high field ESR spectroscopy. The pulse width is around 50 ms. In order to cover this pulse width, the gyrotron can operate during more than 100 ms in pulse length.