Abstract: A heat exchanger delivers a pressurized dry gas stream cooled to an essentially constant temperature. The gas stream circulates in a coil with a functional part immersed in a liquid fraction of a second gas in a chamber of a corresponding container, whereby a portion of the wall of the container with the chamber contacts a liquid fraction of a third gas, providing a condensation surface for the second gas. The container containing the second pressurized gas is airtight. The condensation surface is dimensioned to allow absorption of a predetermined caloric power by the gas in the chamber without significant variation of temperature/pressure. Included is a monitored variable heater of the bath of the liquid fraction of the residual gas in the container, whereby total caloric power released by the circulating gas to be cooled and by the heater is constantly kept approximately equal to the specified caloric power.

Abstract: A power circuit of a coil, includes two power or transmission line segments that are each connected to one of two ends of this coil, the line segments forming with the coil an oscillating circuit exhibiting a determined resonance frequency. The circuit has two line segments each including at least two conductors, of which one is connected to coil, and between them exhibit identical structures and identical lengths of connected conductors, whereby this common length is essentially a multiple of half of the resonance wavelength of the oscillating circuit. The conductors which are connected to coil at one of their ends are connected to one another at their other end by an adjustable symmetrical tuning component that completes this oscillating circuit, which with symmetrical structure is powered by a primary power circuit.

Abstract: A multifrequency power circuit of an NMR coil, includes two power or transmission line segments called principal line segments, each including a segment of a conductor that is attached to the coil, which attached segments together with the coil constitute a first oscillating circuit that exhibits a determined resonance frequency. The principal line segments consist of controlled-impedance multiconductor line segments, each including at least one other conductor segment that is not attached to coil and that extends into the principal line segment beside corresponding respectively attached conductor segment and that exhibits with the latter a capacitive coupling that is distributed along segments located beside or opposite the conductors.

Abstract: A power circuit of a coil, includes two power or transmission line segments that are each connected to one of two ends of this coil, the line segments forming with the coil an oscillating circuit exhibiting a determined resonance frequency. The circuit has two line segments each including at least two conductors, of which one is connected to coil, and between them exhibit identical structures and identical lengths of connected conductors, whereby this common length is essentially a multiple of half of the resonance wavelength of the oscillating circuit. The conductors which are connected to coil at one of their ends are connected to one another at their other end by an adjustable symmetrical tuning component that completes this oscillating circuit, which with symmetrical structure is powered by a primary power circuit.