3 results about "Radiofrequency coil" patented technology

A current sensing system for a magnetic resonance imaging (MRI) scanner operating at 1H and 31P resonant frequencies includes a dual-tuned RF coil with a network of up to two parallel quarter-wavelength transmission lines, each integrated with a PIN diode-coupled shunt capacitor. A multiple half-wavelength transmission line is employed with a corresponding pair of shunt capacitors and PIN diodes. A quarter-wavelength transmission line, coupled with a power amplifier through a matching network of shunt capacitors and PIN diodes, is also included. The configuration parameters are designed to tune the system to the fundamental frequency and its first odd multiple, correlating with the 1H resonant frequency, and to the 31P resonant frequency. The system accurately senses coil currents by detecting voltage variations in the matching network, thereby facilitating precise current measurements at the tuned resonant frequencies without the need for external sensors.

An NMR probe head (1) for performing high-resolution, liquid-state DNP-NMR comprises a corrugated waveguide (3) for mw transmission, arranged along a longitudinal axis Z of the probe head; a system of at least two of mw reflecting mirrors (4-7) for mw beam transmission, focusing and reshaping the beam to match for a sample geometry; at least one RF coil (11,12) for NMR detection mounted in a way to allow mw passage to the sample area, characterized by a cooling system comprising a flow dewar tube (8) for feeding cryogenic fluid mounted at the side of the probe head and parallel to the corrugated waveguide and a thermally isolated sample chamber (26) surrounded by a chamber dewar (9); a sample spinning arrangement being configured to achieve uniform irradiation over a sample volume, to increase the sample volume under mw irradiation, and to reduce sample heating; a sample assembly (13) comprising concentric circular tubes or rods (15, 16) forming constraints for a sample layer (14). This arrangement is capable of exciting in particular even large sample volumes up to ~40 μL.

An NMR-DNP probe head comprises a probe holder for receiving a sample vessel containing a sample substance surrounded by an RF coil, a temperature control device for maintaining the temperature of the sample substance, a microwave guide for supplying microwave radiation into the sample volume, and an illumination device comprising an optical fiber for photoinduced electron excitation of the sample substance in the sample volume. The temperature control device comprises a VT channel through which temperature control fluid can be supplied to the sample vessel during NMR measurement to maintain the temperature of the sample substance, the sample-side end of the optical fiber is arranged in the VT channel, and a deflecting mirror is arranged in the VT channel between the sample-side end of the optical fiber and the sample vessel that directs light exiting the optical fiber onto the sample substance in the sample volume of the sample vessel.