Electricity: measuring and testing – Particle precession resonance – Spectrometer components
Reexamination Certificate
2000-09-18
2004-01-13
Lefkowitz, Edward (Department: 2862)
Electricity: measuring and testing
Particle precession resonance
Spectrometer components
C324S322000
Reexamination Certificate
active
06677751
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a measuring system for nuclear magnetic resonance (NMR) measurements with an NMR probe head containing a cooled NMR receiver resonator for detecting NMR signals, wherein the NMR probe head is connected via transfer lines to one or several cooling systems for supplying two loops with coolants at two different cryogenic temperature levels, wherein each transfer line comprises at least one coolant feed line for transporting the coolant at one of the two temperature levels from the cooling system to the NMR probe head and/or a coolant return line for returning the coolant from the NMR probe head to the cooling system.
A device of this type is e.g. known from U.S. Pat. No. 5,889,456-A.
Cooled NMR probe heads (=CRP=Cryogenic Probe) belong to a new field of NMR instrumentation with very interesting future prospects. Such CRPs have receiver resonators which are cooled down to temperatures as low as possible and are constructed either from normally conducting or superconducting materials. This leads to a significant improvement of the signal-to-noise ratio and thus of the NMR sensitivity.
NMR receiver resonators in the above-mentioned CRPs can be constructed also from several high-frequency receiver coils or coil sets.
It is possible to cool not only the receiver resonator but also further components of the detection system such as the connecting components between the resonator and the pre-amplifier, and the pre-amplifier itself. In general, this leads to further improvement of the NMR sensitivity.
The field of CRPs is still relatively young and at its beginning. CRPs are described e.g. in WO 96/39636, U.S. Pat. No. 5,585,723-A or U.S. Pat. No. 5,585,778-A and cooling means are described in U.S. Pat. No. 5,508,613-A and in the initially cited U.S. Pat. No. 5,889,456-A. The cooling means and the CRPs are connected with each other via transfer lines comprising one, two, or four feed lines preferably designed as plug-ins and described as in U.S. Pat. No. 5,829,791-A.
Cooling of the CRPs is achieved by cooling one to two coolant loops A and B by a cooling source on one side and by using these coolant loops to cool the CRP on the other side.
These coolant loops are pipelines through which cooled helium gas flows. The loop does not have to be a closed loop, it can be open. An open coolant loop is obtained e.g. if a Dewar container with liquid helium is used as a cooling source and the helium gas returning from the cooling process is released to the outside. A first open coolant loop A may as well be connected with a second, also open coolant loop B and become in this manner a closed coolant loop.
The first coolant loop A at the lowest temperature (0 to 70K, preferably 4 to 30K) is always necessary and serves mainly for cooling the NMR resonator. In addition, the coolant loop can be used for a complete or partial cooling of the pre-amplifier and of various electrical and mechanical components between the resonator and the pre-amplifier of the NMR probe head, e.g. coupling networks, filters, feed lines, respectively mounting elements, radiation shields etc.
A second coolant loop B is desired in most cases but not absolutely required. It operates at a higher temperature (e.g. 70K) and serves mainly for complete or partial cooling of the pre-amplifier. It can be used additionally or exclusively for cooling electrical and mechanical components (e.g. electrical filters, RF or other electrical lines, mechanical structural elements, radiation shields etc.).
The cooling medium for the coolant loops is preferably helium gas. The coolant loops are cooled by various cooling sources, i.e. Dewar containers containing liquid helium and one-step or two-step cryo-coolers.
The CRPs contain a cooled receiver resonator and have either none, one or more cooled pre-amplifiers. The receiver resonators are made of passive elements and are preferably cooled to temperatures in the range of 0 to 30K. Depending on the technology used for the pre-amplifiers, one has to check that they are not cooled too much because some electronic components such as e.g. certain semi-conductors may not perform well at too low temperatures. Therefore, temperatures between 70K and 80K are preferred.
Finally, the present state of the art uses a plurality of cooling devices and a plurality of differently structured CRPs which are interconnected in various manners using one or more transfer lines comprising one to two coolant loops, wherein the individual partial units must be adjusted individually to each other for each case.
In contrast thereto, it is the object of the present invention to modify a measuring system of the initially mentioned type with as simple and undemanding means as possible such that completely different CRPs comprising cooling means of any construction can be connected to one another without any modification and in as little time as feasible.
SUMMARY OF THE INVENTION
This object is achieved in accordance with the invention in that the coolant feed lines and the coolant return lines leading to the CRP terminate in a first standardized cryo-connection device to which a matched, also standardized second cryo-connection device, mounted on the probe head, can be coupled to, wherein the second cryo-connection device is connected to coolant feed lines and coolant return lines within the CRP such that two coolant loops can be maintained.
Preferably, only one individual transfer line is provided which is constructed as quadruple transfer line and comprises one coolant feed line and one coolant return line for each of the two coolant loops.
One embodiment of the inventive measuring system is particularly preferred wherein one or more transfer lines are connected rigidly with one of the cooling devices via a connection piece, forming therewith a cooling system which can be connected to an NMR probe head by means of the standardized coupling device. Up to now three different groups of partial units belonging to the cooled measuring system had to be handled i.e. as first group the cooling systems with the cooling devices, as second group the various cooled NMR probe heads and as third group the transfer lines for connecting the cooling systems with the NMR probe heads, wherein the corresponding interfaces between the three groups of partial units had to be designed in a plurality of ways and had to be matched to each other individually according to requirements. In contrast to the described state of the art, the above mentioned embodiment of the invention combines the first and third group of partial units to one single group of cooling systems with standardized cryo-connection devices which can be coupled in a very short time and without any need of further adaptations to the inventive cryo-connection device of the various NMR probe heads of the third group.
In a further development of the above-mentioned embodiment, the connection device of the transfer line is welded or soldered to the cooling system, or alternatively screwed thereto via a flange such that the cooling system is one single piece consisting of the cooling system and the transfer line.
In another embodiment the connection device is releasably connected to the cooling system, preferably as a plug-in connection, such that the two partial units “cooling device” and “transfer line” can be treated individually, if required, e.g. for necessary repairs, or when broken units have to be replaced by other corresponding standard units.
One embodiment of the inventive measuring system is particularly preferred wherein the cryo-connection devices are plug-in-connections. Thereby, the handling of the inventive measuring system becomes particularly simple and time-saving and modifications or extensions or connections can be carried out by less qualified staff. This shows the particular advantage of the invention, which lies in the standardization of the cryo-connection on the probe head and on the transfer line which allows a connection to each other irrespective of the configuration of the probe head and the
Marek Daniel
Triebe Rene
Bruker Biospin AG
Lefkowitz Edward
Vargas Dixomara
Vincent Paul
LandOfFree
Connection system between cryo-cooling systems and cooled... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Connection system between cryo-cooling systems and cooled..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Connection system between cryo-cooling systems and cooled... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3217165