The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Hideki Nakagome - One of the best experts on this subject based on the ideXlab platform.
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gas gap thermal switch for precooling of cryocooler cooled Superconducting Magnets
Advances in cryogenic engineering, 1996Co-Authors: G R Chandratilleke, Y Ohtani, Hideo Hatakeyama, Toru Kuriyama, Hideki NakagomeAbstract:We have developed a heat switch for use with Superconducting Magnets that are cooled by two - stage GM cryocoolers. In developing cryocooler-cooled 6T and 10T Superconducting Magnets, which weigh some tens of kilograms, we have found that shortening cooldown times of this type of Magnets is of vital importance for their wide-spread use. To shorten the magnet cooldown time, a gas-filled thermal switch having a gas-gap configuration was developed; the gap between heat transfer cylinders inside the switch is designed to be 1 mm and is filled with nitrogen. The switch thermally bridges the first and second stages of the cryocooler above 70 K when the switch is “ON.” It de-couples the two stages below 50 K when the switch is “OFF.” It was observed that in the temperature range 70 to 300 K, the switch provides a 80 W refrigeration capacity at the second refrigeration stage, which is about four times higher capacity than the second stage alone can provide. Using a copper block of 40 kg, we demonstrated that the cooldown time from 300 K to 4 K was only a quarter of the time required without the switch.
Mike Seidel - One of the best experts on this subject based on the ideXlab platform.
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a novel beam optics concept in a particle therapy gantry utilizing the advantages of Superconducting Magnets
Zeitschrift Fur Medizinische Physik, 2016Co-Authors: Alexander Gerbershagen, J M Schippers, D Meer, Mike SeidelAbstract:Abstract Purpose A first order design of the beam optics of a Superconducting proton therapy gantry beam is presented. The possibilities of Superconducting Magnets with respect to the beam optics such as strong fields, large apertures and superposition of different multipole fields have been exploited for novel concepts in a gantry. Since various techniques used in existing gantries have been used in our first design steps, some examples of the existing Superconducting gantry designs are described and the necessary requirements of such a gantry are explained. Methods The study of a gantry beam optics design is based on Superconducting combined function Magnets. The simulations have been performed in first order with the conventional beam transport codes. Results The superposition of strong dipole and quadrupole fields generated by Superconducting Magnets enables the introduction of locally achromatic bending sections without increasing the gantry size. A rigorous implementation of such beam optics concepts into the proposed gantry design dramatically increases the momentum acceptance compared to gantries with normal conducting Magnets. In our design this large acceptance has been exploited by the implementation of a degrader within the gantry and a potential possibility to use the same magnetic field for all energies used in a treatment, so that the Superconducting Magnets do not have to vary their fields during a treatment. This also enables very fast beam energy changes, which is beneficial for spreading the Bragg peak over the thickness of the tumor. Conclusions The results show an improvement of its momentum acceptance. Large momentum acceptance in the gantry creates a possibility to implement faster dose application techniques.
Alexander Gerbershagen - One of the best experts on this subject based on the ideXlab platform.
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a novel beam optics concept in a particle therapy gantry utilizing the advantages of Superconducting Magnets
Zeitschrift Fur Medizinische Physik, 2016Co-Authors: Alexander Gerbershagen, J M Schippers, D Meer, Mike SeidelAbstract:Abstract Purpose A first order design of the beam optics of a Superconducting proton therapy gantry beam is presented. The possibilities of Superconducting Magnets with respect to the beam optics such as strong fields, large apertures and superposition of different multipole fields have been exploited for novel concepts in a gantry. Since various techniques used in existing gantries have been used in our first design steps, some examples of the existing Superconducting gantry designs are described and the necessary requirements of such a gantry are explained. Methods The study of a gantry beam optics design is based on Superconducting combined function Magnets. The simulations have been performed in first order with the conventional beam transport codes. Results The superposition of strong dipole and quadrupole fields generated by Superconducting Magnets enables the introduction of locally achromatic bending sections without increasing the gantry size. A rigorous implementation of such beam optics concepts into the proposed gantry design dramatically increases the momentum acceptance compared to gantries with normal conducting Magnets. In our design this large acceptance has been exploited by the implementation of a degrader within the gantry and a potential possibility to use the same magnetic field for all energies used in a treatment, so that the Superconducting Magnets do not have to vary their fields during a treatment. This also enables very fast beam energy changes, which is beneficial for spreading the Bragg peak over the thickness of the tumor. Conclusions The results show an improvement of its momentum acceptance. Large momentum acceptance in the gantry creates a possibility to implement faster dose application techniques.
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alternating gradient canted cosine theta Superconducting Magnets for future compact proton gantries
Physical Review Special Topics-accelerators and Beams, 2015Co-Authors: W Wan, Lucas Brouwer, S Caspi, S Prestemon, Alexander Gerbershagen, J M Schippers, D RobinAbstract:Author(s): Wan, W; Brouwer, L; Caspi, S; Prestemon, S; Gerbershagen, A; Schippers, JM; Robin, D | Abstract: We present a design of Superconducting Magnets, optimized for application in a gantry for proton therapy. We have introduced a new magnet design concept, called an alternating-gradient canted cosine theta (AG-CCT) concept, which is compatible with an achromatic layout. This layout allows a large momentum acceptance. The 15 cm radius of the bore aperture enables the application of pencil beam scanning in front of the SC-magnet. The optical and dynamic performance of a gantry based on these Magnets has been analyzed using the fields derived (via Biot-Savart law) from the actual windings of the AG-CCT combined with the full equations of motion. The results show that with appropriate higher order correction, a large 3D volume can be rapidly scanned with little beam shape distortion. A very big advantage is that all this can be done while keeping the AG-CCT fields fixed. This reduces the need for fast field ramping of the Superconducting Magnets between the successive beam energies used for the scanning in depth and it is important for medical application since this reduces the technical risk (e.g., a quench) associated with fast field changes in Superconducting Magnets. For proton gantries the corresponding Superconducting magnet system holds promise of dramatic reduction in weight. For heavier ion gantries there may furthermore be a significant reduction in size.
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alternating gradient canted cosine theta Superconducting Magnets for future compact proton gantries
Physical Review Special Topics-accelerators and Beams, 2015Co-Authors: W Wan, Lucas Brouwer, S Caspi, S Prestemon, Alexander Gerbershagen, J M Schippers, D RobinAbstract:Author(s): Wan, W; Brouwer, L; Caspi, S; Prestemon, S; Gerbershagen, A; Schippers, JM; Robin, D | Abstract: © 2015 authors. Published by the American Physical Society. We present a design of Superconducting Magnets, optimized for application in a gantry for proton therapy. We have introduced a new magnet design concept, called an alternating-gradient canted cosine theta (AG-CCT) concept, which is compatible with an achromatic layout. This layout allows a large momentum acceptance. The 15 cm radius of the bore aperture enables the application of pencil beam scanning in front of the SC-magnet. The optical and dynamic performance of a gantry based on these Magnets has been analyzed using the fields derived (via Biot-Savart law) from the actual windings of the AG-CCT combined with the full equations of motion. The results show that with appropriate higher order correction, a large 3D volume can be rapidly scanned with little beam shape distortion. A very big advantage is that all this can be done while keeping the AG-CCT fields fixed. This reduces the need for fast field ramping of the Superconducting Magnets between the successive beam energies used for the scanning in depth and it is important for medical application since this reduces the technical risk (e.g., a quench) associated with fast field changes in Superconducting Magnets. For proton gantries the corresponding Superconducting magnet system holds promise of dramatic reduction in weight. For heavier ion gantries there may furthermore be a significant reduction in size.
E Ravaioli - One of the best experts on this subject based on the ideXlab platform.
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cliq based quench protection of a chain of high field Superconducting Magnets
IEEE Transactions on Applied Superconductivity, 2016Co-Authors: E Ravaioli, V Datskov, G Kirby, Michal Maciejewski, Ten H Kate, A P VerweijAbstract:Conventional quench protection systems for high-magnetic-field Superconducting Magnets are based on external heaters composed of resistive strips in close contact with the coil and rely on thermal diffusion across insulation layers on the order of tens of micrometers. The large contact areas between the coil and the heater strips, and the thin insulation between them required for an effective protection constitute a significant risk of electrical breakdown and one of the most common causes of magnet damage. Coupling-loss-induced quench (CLIQ) technology offers a valid option for a time- and cost-effective repair of Magnets with failing heater-based protection systems. In fact, its effective heating mechanism utilizing coupling loss, its robust electrical design, and its fast implementation, as compared to alternative repair options, constitute definite advantages over the conventional technology. In the past years, CLIQ was successfully implemented on various coils in a single-magnet configuration. Now the design of a CLIQ-based protection system integrated in a chain of series-connected Magnets is presented. The protection of a chain of Superconducting Magnets usually is considerably more challenging than the protection of stand-alone Magnets due to the increased energy stored in the circuit and the presence of transitory effects. The effectiveness of this new method is demonstrated by means of electrothermal simulations modeling the transition to the normal state and the temperature evolution in one quenched magnet, and the electrodynamics of the entire magnet chain.
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cliq a new quench protection technology for Superconducting Magnets
2015Co-Authors: E RavaioliAbstract:CLIQ, the Coupling-Loss Induced Quench system, is a new method for protecting Superconducting Magnets after a sudden transition to the normal state. It offers significant advantages over the conventional technology due to its effective mechanism for heating the superconductor relying on coupling loss and its robust electrical design, which makes it more reliable and less interfering with the coil winding process. The analysis of the electro-magnetic and thermal transients during and after a CLIQ discharge allows identifying the system parameters that affect the system performance and defining guidelines for implementing this technology on coils of various characteristics. Most existing Superconducting Magnets can be protected by CLIQ as convincingly shown by test results performed on Magnets of different sizes, superconductor types, geometries, cables and strand parameters. Experimental results are successfully reproduced by means of a novel technique for modeling non-linear dynamic effects in Superconducting Magnets. The design of future Magnets can be adapted for improving the performance of a CLIQ-based protection system in terms of lower hot-spot temperature, safer electrical design, as well as reduced size and cost. The impact of the proposed measures, including modifications to the composition of the superconductor and addition of multiple CLIQ terminals, are analyzed and discussed. CLIQ’s fast and relatively homogeneous transfer of the coil to the normal state can enable safe magnet operation at energy densities presently incompatible with the performance of other protection systems. CLIQ technology has rapidly reached maturity and is ready for implementation on present and future high field Superconducting Magnets.
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a new hybrid protection system for high field Superconducting Magnets
Superconductor Science and Technology, 2014Co-Authors: E Ravaioli, V Datskov, G Kirby, H Ten H J Kate, A P VerweijAbstract:The new generation of high-field Superconducting accelerator Magnets poses a challenge concerning the protection of the magnet coil in the case of a quench. The very high stored energy per unit volume requires a fast and efficient quench heating system in order to avoid damage due to overheating. A new protection system for Superconducting Magnets is presented, comprising a combination of a novel coupling-loss induced quench (CLIQ) system and conventional quench heaters. CLIQ can provoke a very fast transition to the normal state in coil windings by introducing coupling loss and thus heat in the coil's conductor. The advantage of the hybrid protection system is a global transition, resulting in a much faster current decay, a significantly lower hot-spot temperature, and a more homogeneous temperature distribution in the magnet's coil.
Zhiquan Song - One of the best experts on this subject based on the ideXlab platform.
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progress of dc quench protection switch for Superconducting fusion reactors
Conference on Industrial Electronics and Applications, 2020Co-Authors: Cunwen Tang, Zhiquan SongAbstract:The Superconducting Magnets are the most expensive and important components for a magnetic confinement thermonuclear fusion device. The high-intensity magnetic fields produced by high density DC current are used to confine and shape the high-temperature plasma in experiments. Therefore, the study of DC quench protection switches is extremely necessary and meaningful for the safety operation of Superconducting Magnets. Different types of switch have been studied based on various circuit requirements and parameters, such as interruption time, current and voltage. This paper reviewed the developing process of quench protection switch and summarized the respective characteristics of direct interruption commutation switch, artificial zero-crossing commutation switch and full-controlled active commutation switch. Finally, the paper expounded the recent development of three-level contacts hybrid DC breaker technology for next generation fusion reactor.
