A Broadband High-Power Amplifier System for High-Field Pulsed DNP at 263 GHz

To further improve DNP-NMR systems, a transition from continuous wave sources to amplifiers, which coherently amplify arbitrary pulse sequences and therefore offer more flexibility, is desired. Additionally, higher power levels in the range of multiple 100W are desired. To accommodate this, a hybrid amplifier system, consisting of a solid state pre-amplifier system and vacuum tube power amplifier, is proposed. The current state of developments of these components are summarized and the challenges and upcoming work are laid out. The main obstacles are determined as the solid state pre-amplifier capable of generating a 1W input signal for the subsequent power amplifier, the manufacturing of the helical interaction region and assembly of the entire tube with tight tolerances and last but not least, a sufficient isolation between the two stages of amplification to prevent the damage to the solid state device by reflected power.