The development of new, high-frequency solid-state diode sources capable of operating at 263 GHz, together with an optimized stator design for improved millimeter-wave coupling to the NMR sample, have enabled low-power DNP experiments at 263 GHz/400 MHz. With 250 mW output power, signal enhancements as high as 120 are achieved on standard samples – approximately 1/3 of the maximal enhancement available with high-power gyrotrons under similar conditions. Diode-based sources have a number of advantages over vacuum tube devices: they emit a pure mode, can be rapidly frequency-swept over a wide range of frequencies, have reproducible output power over this range, and have excellent output stability. By virtue of their small size, low thermal footprint, and lack of facility requirements, solid-state diodes are also considerably cheaper to operate and maintain than high-power vacuum tube devices. In light of these features, and anticipating further improvements in terms of available output power, solid-state diodes are likely to find widespread use in DNP and contribute to further advances in the field.

能够在 263 GHz 下运行的新型高频固态二极管源的开发，以及优化的定子设计以改善与 NMR 样品的毫米波耦合，已实现了 263 GHz/400 MHz 下的低功率 DNP 实验. 凭借 250 mW 的输出功率，在标准样品上可实现高达 120 的信号增强——大约是类似条件下大功率回旋管最大增强的 1/3。与真空管器件相比，基于二极管的源具有许多优点：它们发出纯模式，可以在很宽的频率范围内快速扫频，在该范围内具有可再现的输出功率，并且具有出色的输出稳定性。凭借其小尺寸、低热足迹和缺乏设施要求，固态二极管的操作和维护成本也比大功率真空管设备便宜得多。鉴于这些特点，并预计在可用输出功率方面的进一步改进，固态二极管可能会在 DNP 中得到广泛使用，并有助于该领域的进一步发展。