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Detectors, Relative Dosimetry, and Microdosimetry
Published in Harald Paganetti, Proton Therapy Physics, 2018
Another novel solid-state detector that has been proposed is based on the Inductive Superconductive Transition Edge Sensor (ISTED), which itself is based on a Superconducting Quantum Interference Device, or SQUID. An ISTED contains the signal-generating superconducting layer within the SQUID loop, and by depositing a tissue-equivalent layer on top of the superconducting layer, it can act as a tissue-equivalent microdosimeter with an identical size and shape as the biological site of interest [70]. The energy deposition by an ionizing event in the absorber heats up the superconducting layer, which in turn causes a change in the inductive coupling between the superconducting layer and the SQUID loop, which can be measured as a change in voltage across the branches of the loop. The main drawback is that it requires operation in a cryostat, increasing the external dimensions and limiting its portability. The contamination signal from direct ionizations within the superconducting layers also needs to be corrected for Ref. [71].
Cryogenic Cooling Strategies
Published in Raja Sekhar Dondapati, High-Temperature Superconducting Devices for Energy Applications, 2020
Sudheer Thadela, Raja Sekhar Dondapati
A cryostat is employed for achieving the desired cryogenic environment. A cryostat comprises of a double-walled evacuated vessel, which is cold within and stationary, similar to the Dewar flask, in order to maintain cryogenic temperatures, as shown in Figure 2.4. Such low temperatures are maintained using a refrigeration method or cryogenic fluids, depending upon the specification. Moreover, such vessels also act like pressure vessels during risky and hazardous circumstances. The typical size varies from cryocans utilized in laboratories for medical research to fusion reactor vessels for keeping the magnet cool at its operating temperature. The construction of a bath cryostat is similar in construction to a vessel filled with cryogens. A cold plate is in thermal contact with the cryogen, which is replenished as it boils away. Moreover, the boiling of cryogens, such as LHe, can be further used to cool the thermal shields placed outside the LHe bath. The boiling rate can be structurally controlled by installing several concentric layers of shield, which would gradually decrease the temperature. A closed-cycle cryostat consists of a chamber through which helium vapor is pumped and an external mechanical refrigerator that extracts helium exhaust, which is further cooled and recycled. Such a cryostat does not need refilling with helium; however, it demands large amounts of electric power. Within these cryostats, the magnet or the specimen is cooled by attaching a link, which is in thermal contact with it, to a metallic cold plate of a cryocooler. However, for laboratory experiments, continuous-flow cryostats have gained more attention, where LHe cools it from a storage Dewar flask. Continuous replenishment of LHe takes place by its steady flow. Such configurations do not require electric power; however, its drawback is the large quantity of LHe consumed during the operation. Hence, such facilities are encouraged to capture helium vented through the cryostat.
High Temperature Superconducting Motors
Published in Ranjan Vepa, Electric Aircraft Dynamics, 2020
Several research and development groups worldwide are involved in the design of HTS motors for aircraft propulsion. HTS motors i.e. motors with armature and field windings made of HTS wires or tapes that are encased within a vacuum-sealed cryostat, so the temperature of the stator and rotor are in the superconductivity domain, may be used for aircraft propulsion. The cryostat is essentially a refrigeration system or cylinder which uses the cold circulating gas in a closed loop, and continuously maintains the HTS field winding at the desired low cryogenic temperature. Cryostats required for aerospace propulsion have been shown to require relatively low power as they need to mainly compensate for the power losses in the HTS coils. The design of an integrated, low power-consuming cryostat is the key to the use of HTS motors for aircraft applications. Pienkos et al. [36] describe the design of a small HTS motor, including the required cryostat that is integrated within the hub of the aircraft’s propeller (see also Masson et al. [11] and Luongo et al. [12]). Vratny et al. [37] presented the design of an optimal HTS motor and the associated controller architecture with regard to efficiency and mass for all electric aircraft propulsion. They have estimated that the specific power requirements for the HTS motor could vary between 10 to 40 kW/kg with very high propulsive efficiencies, while the power required for the cryostat would be less than 0.33 kW/kg. The study clearly points to the large requirements of stored electric power in the form of batteries. Several research groups are also investigating the feasibility of different superconducting technologies not only for the storage of electric power, but also for electromagnetic launch to assist civil aircraft to take off. This would reduce the total in-flight power requirements which in turn would reduce the required size of the batteries for electric power storage. Haran et al. [38] have presented a technology roadmap for the development of superconducting machines for aircraft propulsion and other applications.
Temperature-dependence of plasticity and fracture in an Al-Cu-Li alloy
Published in Philosophical Magazine, 2020
Niraj Nayan, Sivasambu Mahesh, M. J. N. V. Prasad, S. V. S. N. Murthy, Indradev Samajdar
Tensile tests were also performed at temperatures of and , as per ASTM E1450-09 with displacement rates of () on tensile specimens having dimensions with a gauge length of . Testing was performed using servo hydraulic Universal testing machine (UTM) with a cryostat attached. The cryostat is a vacuum insulated casing containing heat exchanger, copper radiation shield and a central sample space designed to accept the load string. Liquid nitrogen was used to cool the specimen to and . Rhodium-Iron resistance temperature detector (RTD) was used to measure the temperature of the specimen. The temperature of the cryostat was maintained to an accuracy of with the help of regularisation of tank pressure of the container and flow rate of cryogens. Both are dynamically controlled to maintain the required test temperature. At the two cryogenic temperatures, it was not possible to measure the strain using a gauge extensometer. Crosshead displacement readings were therefore used to infer strains.
An Iterative and Cost-Based Approach for Optimal SFCL Allocation in Fault Level-Constrained Meshed Networks
Published in Electric Power Components and Systems, 2020
Mostafa Hosseinpour, Javad Sadeh
In order to reduce the temperature of superconducting materials which rise significantly during operation, the cryostat filled with liquid nitrogen and connected to a cooling system is used. In R-SFCLs, presuming a series connection topology for the superconductive, the cooling system is continuously active and lowering the temperature. But the X-SFCL only requires the cooling system to initiate of any performance. Nevertheless, an X-SFCL, due to its core and coils, weighs and sizes almost four times a similar R-SFCL. Since the X-SFCL connects via a special transformer, it is costly investment in comparison to the resistive types [23–25].
Design of a Cryostat for Spectroscopic Investigation of All Hydrogen Isotopologues in the Solid, Liquid, and Gaseous Phases
Published in Fusion Science and Technology, 2020
Bennet Krasch, Robin Größle, Daniel Kuntz, Sebastian Mirz
Figure 2 shows a longitudinal cut of the T2ApIR cryostat. The cryostat consists of two elements: a cube and a cross, both made of stainless steel (type X6CrNiMoTi17-12-2). The total volume of the cryostat without any instrumentation is 15.6 and 14.3 dm3 with instrumentation as shown in Fig. 2.