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[EN] The present invention relates to a cryocooler suitable for gas liquefaction applications, that comprises a coldhead (1) with one or more refrigeration stages (2, 3); further comprising: a refrigerator compressor (4) for distributing compressed gas-phase cryogen inside the coldhead (1); a heat exchanging coil (9) arranged at least partially around the external region of the coldhead (1); at least one extraction orifice (8) communicating a gas circulation circuit (5) inside the coldhead (1) with the heat exchanging coil (9); acting said extraction orifice/s (8) as pass-through port/s which allow the gas inside the coldhead (1) to flow through the inside of the heat exchanger coil (9) for exchanging heat with the exterior thereof, and wherein the heat exchanging coil (9) is adapted to connect and redirect the gas to one return port (8') connected to the gas circulation circuit (5). Another object of the invention relates to a cryogen-gas liquefaction system (11) and a method for liquefaction of gases that comprises said system (11), [FR] La présente invention concerne un refroidisseur cryogénique conçu pour des applications de liquéfaction de gaz, qui comprend une tête froide (1) dotée d'un ou de plusieurs étages de réfrigération (2, 3) ; comprenant en outre : un compresseur de réfrigérateur (4) pour distribuer un cryogène en phase gazeuse comprimé à l'intérieur de la tête froide (1) ; une bobine d'échangeur de chaleur (9) disposée au moins partiellement autour de la région externe de la tête froide (1) ; au moins un orifice d'extraction (8) communiquant un circuit de circulation de gaz (5) à l'intérieur de la tête froide (1) avec la bobine d'échange de chaleur (9) ; faire fonctionner ledit ou lesdits orifices d'extraction (8) en tant qu'orifices de passage qui permettent au gaz à l'intérieur de la culasse (1) de s'écouler à travers l'intérieur de la bobine d'échangeur de chaleur (9) pour échanger de la chaleur avec l'extérieur de celui-ci, et la bobine d'échangeur de chaleur (9) étant conçue pour connecter et rediriger le gaz vers un orifice de retour (8') raccordé au circuit de circulation de gaz (5). Un autre objet de l'invention concerne un système de liquéfaction de gaz cryogénique (11) et un procédé de liquéfaction de gaz qui comprend ledit système (11), Universidad de Zaragoza, Consejo Superior de Investigaciones Científicas (España), A3 Informe de búsqueda internacional

Resumen del trabajo presentado a la XXXVII Reunión Bienal de la Real Sociedad Española de Física celebrada en Zaragoza del 15 al 19 de julio de 2019., The presence of Hydrogen (H2) traces in LHe has disastrous consequences for some laboratory equipment such as evaporation cryostats, PPMS and MPMS. The working principle of those equipment to achieve temperatures below 4.2 K consists in pumping LHe through a capillary tube. If LHe contains H2 traces, that capillary will get blocked after some time. In order to unblock it, it is needed to heat the equipment at room temperature (RT) with the loss of liquid He and time. With the aim to solve this problem, the University of Zaragoza in collaboration with Quantum Design company developed a method to produce H2 free LHe. In this work, we present a study to determine what is the minimum H2 concentration in He gas that can generate blockages when the He gas is liquified. To carry out this proposal, we have developed an experimental setup to produce LHe contaminated with H2 in a controller manner. This setup can be divided in two stages (see figure): the first one consists in mixing the He gas (at RT and pressure larger than atmospheric) with a known H2 concentration to then be liquified (at 4.2 K and atmospheric pressure), whereas the second one consists in the detection of H2 traces present in the liquified He-H2 gas mixture by using a H2 detector developed by us, whose effectiveness has been proved in other labs around the world. This device consists of a flow microimpedance assembled to a stainless steel thin tube. The microimpedance is immersed in LHe while the other end of the tube is connected to a vacuum pump and a pressure sensor. If the tested LHe contains H2 traces (with an enough concentration to produce blockages), the pressure reading will decrease (in a few minutes) to the baseline of the vacuum pump.

Trabajo presentado al 8º Foro Europeo para la Ciencia, Tecnología e Innovación (TRANSFIERE), celebrado en Zaragoza (España) del 13 al 14 de febrero de 2019.

Trabajo presentado al ATL user workshop, celebrado en Zaragoza del 23 al 24 de octubre de 2018.

Trabajo presentado al ATL user workshop, celebrado en Zaragoza del 23 al 24 de octubre de 2018.

Trabajo presentado al X Meeting de GEFES (División de Física de la Materia Condensada de la Real Sociedad Española de Física), celebrado en Valencia del 24 al 26 de enero de 2018., Measurement systems for low temperature research in material science commonly use 4He evaporation cooling techniques based on impedances made with capillary tubes. These techniques use isenthalpic gas expansion to extend the temperature range achievable from 4,2 K, the liquid helium normal boiling point temperature, down to 1 K. However, they have a worldwide reported issue: the occasional blockage of the impedance that generates nuisances and a waste of helium and financial resources. We have recently shown that the mechanism of capillary blockage is the freeze of molecular hydrogen traces present in the liquid helium bath when the liquid helium is not sufficiently clean. Here we present a simple device based on a pumping system with a micro impedance to test the cleanliness of the liquid helium. We used a Focused Ion Beam (FIB) to drill the impedance hole in a copper foil with a thickness of 35 μm. This device makes possible to test the liquid helium quality in a few minutes before transferring the liquid into a blockage sensitive apparatus., The authors greatly acknowledge the financial support from the Spanish Ministry of economy and Competitiveness through the Project Nº MAT2015-64083-R, in addition to European Union FEDER funds.

Trabajo presentado al ATL user workshop, celebrado en Zaragoza del 23 al 24 de octubre de 2018.

Trabajo presentado al II Congreso del Instituto de Ciencia de Materiales de Aragón: “Materiales para los retos de la sociedad", celebrado en Jaca (Huesca) del 2 al 3 de febrero de 2017.

Five-coordinate oxo-derivatives [NBu 4 ][MO(C 6 F 5 ) 4 ] (1) have been prepared for the heavier Group 6 elements: 1-Mo and 1-W. The magnetic properties of that salts have been studied by a combination of Electron paramagnetic resonance (EPR), calorimetric and magnetochemical techniques, pointing out the existence of weak ferromagnetic interactions. These have been correlated with the arrangement of the magnetic units in the crystal.

[ES] Se describe una planta de recuperación de helio sin pérdidas y que permite el suministro continuo de helio en equipos que requieran dicho elemento para refrigeración, o para almacenarlo cuando no sea necesaria su distribución., [EN] The present invention relates to a helium-recovery plant that does not generate losses and that allows the continuous supply ofhelium in equipment requiring said element for refrigeration, or for the storage thereofwhen the distribution thereof is mmecessary., Consejo Superior de Investigaciones Científicas (España), Universidad de Zaragoza, A1 Solicitud de patente con informe sobre el estado de la técnica

Planta de recuperación de helio.Se describe una planta de recuperación de helio sin pérdidas y que permite el suministro continuo de helio en equipos que requieran dicho elemento para refrigeración, o para almacenarlo cuando no sea necesaria su distribución., Consejo Superior de Investigaciones Científicas (España), Universidad de Zaragoza, B1 Patente sin examen previo

Trabajo presentado al 19th International Cryocooler Conference, celebrada en San Diego, California (US) del 20 al 23 de junio de 2016., A cryocooler based helium recovery plant designed to store, compress and purify helium gas collected from one or more helium-using instruments, as well as to liquefy and redistribute the purified gas within a closed system, is presented. The recovery plant is composed to match the purification and liquefaction rate of the system with the consumption rate of the coupled instruments in an attempt to achieve zero loss. In addition, extreme purity helium (gas and liquid) is obtained by the combination of cryo-condensation of impurities and further chemical adsorption by a getter. Problems like clogging of low temperature impedances by impurities normally present in helium have been definitely solved using this plant concept., The authors express their gratitude for the financial support from the Spanish Ministry of Economy and Competitiveness through project MAT2015-64083-R.

[EN] The present invention relates to a method and a system for cooling liquid helium, that allows working without losses at temperatures under 2.5 K and at atmospheric pressure. The invention is preferably applicable to liquid helium baths for use in an NMR instrument, MRI instrument or instrument for measuring physical properties, and comprises: a cryostat (1) housing the cryogenic liquid which comprises inside thereof a superconducting device belonging to said instrument; a cryocooler (3) thermally connected to the cryostat; and an inlet source for cryogenic gas connected to the cryostat. Advantageously, the invention additionally comprises a subsystem (5) for regulating the pressure in the cryostat, operated by means for controlling the inlet of cryogenic gas into said cryostat., [ES] La presente invención se refiere a un método y un sistema para enfriar helio líquido, que permite trabajar sin pérdidas a temperaturas inferiores a 2,5 K y a presión atmosférica. La invención es preferiblemente aplicable a baños de helio líquido para uso en un instrumento de RMN, instrumento de IRM o instrumento para medir propiedades físicas, y comprende: un criostato (1) que aloja el líquido criogénico que comprende dentro de los mismos un dispositivo superconductor que pertenece a dicho instrumento; un refrigerador criogénico (3) conectado térmicamente al criostato; y una fuente de entrada para gas criogénico conectado al criostato. Ventajosamente, la invención comprende adicionalmente un subsistema (5) para regular la presión en el criostato, operado por medios para controlar la entrada de gas criogénico en dicho criostato., Universidad de Zaragoza, Consejo Superior de Investigaciones Científicas (España), A1 Solicitud de patente con informe sobre el estado de la técnica

A system and a method for liquefaction of gases which are utilized in their liquid state as refrigerants in applications that require low temperatures, throughout various pressure ranges, from slightly above atmospheric pressures to pressures near the critical point. The system and method are based on closed-cycle cryocoolers and utilize the thermodynamic properties of the gas to achieve optimal liquefaction rates., Consejo Superior de Investigaciones Científicas (España), Universidad de Zaragoza, GWR Instruments, Inc., A2 Solicitud de patente sin informe sobre el estado de la técnica

Tesis Doctoral presentada por el Licenciado Miguel Gabal Lanau en el Departamento de Física de la Materia Condensada del Instituto de Ciencia de Materiales de Aragón (Universidad de Zaragoza)., The purpose of this thesis is to present the development of an emerging technology for small-scale helium recovery, focusing in all the needed steps: helium recovery, helium purification and helium liquefaction. This technology uses cryocoolers for both, the liquefaction and the purification, in a novel way: the gas is simply in direct thermal contact with the cryocooler, and, the process takes advantage smartly of the outstanding helium properties. The technology is efficient, modular and scalable, making feasible the installation in almost any facility, from very small size (e.g. average helium consumption less than 1 L/day), to medium size (e.g. 200 L/day). Finally, we present the ultra-pure liquid helium concept “Clean Helium” (hydrogen-free liquid helium) that has been produced with the technology presented here. “Clean Helium” solves a global issue: The blocking of fine capillary tubes used as flow impedances in 4He evaporation cryostats to achieve temperatures below 4.2 K.