Cryotechnology and Cryopumps

Day, Christian

doi:10.1002/9783527688265.ch12

Cited by 3 publications

(5 citation statements)

References 41 publications

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“…In EDGE2D/EIRENE the pumping albedo is defined to be equal to [1-sticking probability of H 2 (or D 2 ) gas to the cryosurface]. The sticking probabilities were shown to be higher for deuterium than for hydrogen from neutral beam test bed results [33], which implies lower albedo values for deuterium than for hydrogen, in qualitative agreement with the EDGE2D/EIRENE simulations.…”

Section: L-modesupporting

confidence: 61%

Isotope effects on L-H threshold and confinement in tokamak plasmas

Maggi

Weisen

Hillesheim

et al. 2017

Plasma Phys. Control. Fusion

111

191

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The dependence of plasma transport and confinement on the main hydrogenic ion isotope mass is of fundamental importance for understanding turbulent transport and, therefore, for accurate extrapolations of confinement from present tokamak experiments, which typically use a single hydrogen isotope, to burning plasmas such as ITER, which will operate in deuterium-tritium mixtures. Knowledge of the dependence of plasma properties and edge transport barrier formation on main ion species is critical in view of the initial, low-activation phase of ITER operations in hydrogen or helium and of its implications on the subsequent operation in deuterium-tritium. The favourable scaling of global energy confinement time with isotope mass, which has been observed in many tokamak experiments, remains largely unexplained theoretically. Moreover, the mass scaling observed in experiments varies depending on the plasma edge conditions. In preparation for upcoming deuterium-tritium experiments in the JET tokamak with the ITER-like Be/W Wall (JET-ILW), a thorough experimental investigation of isotope effects in hydrogen, deuterium and tritium plasmas is being carried out, in order to provide stringent tests of plasma energy, particle and momentum transport models. Recent hydrogen and deuterium isotope experiments in JET-ILW on L-H power threshold, L-mode and H-mode confinement are reviewed and discussed in the context of past and more recent isotope experiments in tokamak plasmas, highlighting common elements as well as contrasting observations that have been reported. The experimental findings are discussed in the context of fundamental aspects of plasma transport models.

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Section: L-modesupporting

confidence: 61%

Isotope effects on L-H threshold and confinement in tokamak plasmas

Maggi

Weisen

Hillesheim

et al. 2017

Plasma Phys. Control. Fusion

111

191

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“…The pump albedo was set to 0.4 for H and to 0.7 for D to obtain a match of the upstream profiles for these two discharges. However, these values are not consistent with testbed results on the sticking coefficients (α s ) of H 2 and D 2 at a cryopump surface [60,61]. The sticking coefficient is the ratio of the number of particles sticking to the cryosurface related to the total number of particles impinging on it.…”

Section: Appendix a Pump Albedo In Edge2d-eirene For H And Dcontrasting

confidence: 58%

“…The sub-divertor structures and the cryopump are not modeled in these EIRENE simulations; thus, a oneto-one comparison between the albedo defined in EDGE2D-EIRENE and the testbed results for the sticking coefficients on a cryosurface is not possible, but the albedo is roughly proportional to (1 − α s ). The testbed results show that the sticking coefficient is higher in D than in H [60,61], implying lower albedo in D than in H in contrast to the EDGE2D-EIRENE pump albedo settings. A possible reason for this disagreement could be that the much hotter ions, electrons and neutrals in the SOL of the H discharge may have resulted in different neutral recycling at the wall.…”

Section: Appendix a Pump Albedo In Edge2d-eirene For H And Dmentioning

confidence: 86%

Isotope dependence of the type I ELMy H-mode pedestal in JET-ILW hydrogen and deuterium plasmas

Horváth¹,

Maggi²,

Chankin³

et al. 2021

Nucl. Fusion

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The pedestal structure, edge transport and linear MHD stability have been analyzed in a series of JET with the ITER-like wall hydrogen (H) and deuterium (D) type I ELMy H-mode plasmas. The pedestal pressure is typically higher in D than in H at the same input power and gas rate, with the difference mainly due to lower density in H than in D (Maggi et al (JET Contributors) 2018 Plasma Phys. Control. Fusion 60 014045). A power balance analysis of the pedestal has shown that higher inter-ELM separatrix loss power is required in H than in D to maintain a similar pedestal top pressure. This is qualitatively consistent with a set of interpretative EDGE2D-EIRENE simulations for H and D plasmas, showing that higher edge particle and heat transport coefficients are needed in H than in D to match the experimental profiles. It has also been concluded that the difference in neutral penetration between H and D leads only to minor changes in the upstream density profiles and with trends opposite to experimental observations. This implies that neutral penetration has a minor role in setting the difference between H and D pedestals, but higher ELM and/or inter-ELM transport are likely to be the main players. The interpretative EDGE2D-EIRENE simulations, with simultaneous upstream and outer divertor target profile constraints, have indicated higher separatrix electron temperature in H than in D for a pair of discharges at low fueling gas rate and similar stored energy (which required higher input power in H than in D at the same gas rate). The isotope dependence of linear MHD pedestal stability has been found to be small, but if a higher separatrix temperature is considered in H than in D, this could lead to destabilization of peeling-ballooning modes and shrinking of the stability boundary, qualitatively consistent with the reduced pedestal confinement in H.

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“…Cryogenic pumps are used for elevating liquid air pressure during discharging, which should be able to withstand and operate in extremely cold environment. They can be grouped into bath cryo-pumps, refrigerator-cooled cryo-pumps and helium-cooled cryo-pumps categories [104]. There have been very few studies focusing on cryogenic pumps for LAES, which may be due to the minor effect of cryogenic pump efficiency on the RTE of LAES systems.…”

Section: Cryogenic Pumpsmentioning

confidence: 99%

“…These steady-state assumptions often deviate from actual situations, particularly during start-up, shut-down, and load-following (a key function for storage) periods, dynamic simulation is essential to ensure correct designs, realistic system-level performance prediction for economic analyses, and safe and smooth operations of real-world LAES systems. Several studies have been found in the literature on the transient behaviour of packed-bed thermal stores for LAES plants [37,83,104,105,109], but the modelling of other components are under the steady-state conditions. Sciacovelli et al [37] showed that the specific liquefaction work could be increased by ∼25% by altering the cold end temperature of the cold box, but the transient behaviour of the packed bed has no significant effect on the specific work output of the expansion process.…”

Section: Dynamic Modellingmentioning

confidence: 99%

Liquid air energy storage technology: a comprehensive review of research, development and deployment

Liang

Zhang²,

Lin³

et al. 2023

Prog. Energy

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Liquid air energy storage (LAES) uses air as both the storage medium and working fluid, it falls into the broad category of thermo-mechanical energy storage technologies. Such a technology offers several advantages including high energy density and scalability, cost-competitiveness and non-geographical constraints, and hence has attracted a growing interest in recent years. As a result, several reviews have been published on the topic. However, these reviews covered little in the following aspects of LAES: dynamic simulation and optimisation, key components for LAES, LAES applications through integration, and unified economic model and cost models for LAES. This article provides a comprehensive review on the LAES technology and fills the above gaps. Apart from applications in electrical grids such as peak-shaving, load shifting, and dealing with intermittency of renewable generation, the review also shows a diverse range of other LAES applications through integration, including waste heat and cold energy recovery and utilisation, multi-energy-vector service provision, and sector coupling for chemical production and carbon capture. The review also led to the recommendation of several areas of LAES for future research and development, including dynamic characteristics of whole LAES system integrated with renewables and end users; thermo-economic and dynamic optimization of stand-alone LAES and integrated systems; and experimental study on commercial systems.

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Cryotechnology and Cryopumps

Cited by 3 publications

References 41 publications

Isotope effects on L-H threshold and confinement in tokamak plasmas

Isotope effects on L-H threshold and confinement in tokamak plasmas

Isotope dependence of the type I ELMy H-mode pedestal in JET-ILW hydrogen and deuterium plasmas

Liquid air energy storage technology: a comprehensive review of research, development and deployment

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