VACUUM TEMPERATURE INSERT FOR 95 GHZ SPECTROMETRY

Cornell University, Ithaca NY

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Abstract

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. As described elsewhere in this section, we have recently installed a 9T cryogen-free superconducting magnet for the ACERT 95GHz c.w./pulse spectrometer. The wide bore of this magnet, 89 mm, permits the use of a large-sample vacuum temperature insert (VTI) which can accommodate our existing and contemplated future quasioptical resonator structures. For the instant application, we have chosen a modified Janis Research non-optical SuperTran-VP (STVP-200) cryostat designed for NMR spectroscopy. This continuous flow cryostat maximizes the internal sample space while still minimizing the cryostat outside diameter, providing a large 2.5" sample space while fitting within our 89 mm bore magnet. A temperature range of 1.4 K to 325 K is accessible with this insert. Installation of the STVP-200 VTI is currently in progress and will be initially implemented with an adaptation of the previous 95GHz spectrometer bridge support table. Because the cryogen-free magnet includes a reciprocating pump which generates significant vibrations, the VTI must be physically isolated from the magnet. This will initially be accomplished by suspending its support plate from the modified spectrometer bridge undercarriage frame with stiff triangular sideplates, and, in the aluminum strutwork configuration that will replace it later in summer 2008, from cross-support struts attached to the main frame members. Temperature regulation of the VTI sample space will be maintained using the present 95GHz spectrometer system's Lakeshore model 331Cryogenic Temperature Controller.