This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We have acquired a state-of-the-art precision high-power switching power supply (15KW Lambda Genesys series) to replace the older Varian 5KW linear supply presently employed as the main magnet power source for the 16GHz ESR pulse microscope. The replacement switching power supply provides a low-noise, well-regulated output in a very high power density package that includes a number of I/O options for direct computer and LAN control. A thorough investigation of radiated and conducted radiofrequency noise for this power supply series has resulted in the vendor's supplying supplemental qualifying proof of its suitability for sensitive applications such as NMR and ESR. This supply will be incorporated into a host computer programmable regulation system consisting of the current Hall system (based on Lakeshore 475) and a proprietary field/frequency lock (FFL) r.f. detector/processor. In fall of 2008 this system will replace the existing FFL patch (Varian)/magnet power source. A second, similar 15KW power supply has been acquired for the 35GHz ESRM magnet, which will also utilize a hybrid Hall/FFL field regulation system. Consequently, our expectation is that the experience in design, construction and implementation of the first field-regulated magnet power source will be gainfully applied to the second system intended for the 35GHz ESR microscope.