The 263 GHz klystron is a continuous-wave microwave source designed and manufactured for extended DNP NMR at 400 MHz 1H frequency and 100 K sample temperature. The klystron provides a DNP option with lower purchase price, operating costs, footprint, and facility requirements compared to the gyrotron product line while retaining high DNP sensitivity and stability. At 5 W output power, it reaches 90-100% DNP efficiency on biological samples and small molecules in frozen solution while dense material samples perform at > 80% compared to the 263 GHz gyrotron.
The system assembly consists of: (1) extended interaction klystron oscillator (EIK), (2) a control system with graphical user interface, safety interlocks, power supply and cooling network, and (3) a low-loss microwave transmission line. It is compatible with a 400 WB Ascend DNP solid-state NMR spectrometer and Bruker low-temperature MAS (LTMAS) probes.