The ESS spoke cavity cryomodules

Bousson, S.; Darve, Christine; Duthil, Patxi; Elias, Nuno; Molloy, S.; Reynet, D.; Thermeau, Jean‐Pierre

doi:10.1063/1.4860766

Cited by 7 publications

(4 citation statements)

References 3 publications

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“…Such a theory would also need to explain how degrees of freedom disappear when space contracts, as during black hole formation. Although some 7 More recent versions of the holographic principle have focused on the entropy of 3D light-sheets rather than 3D volumes, evading the implications below [98,99]. 8 An even more extreme example occurs if a Planck-scale region with a mere handful of degrees of freedom generates a whole new universe with say 10 120 degrees of freedom via the Farhi-Guth-Guven mechanism [100].…”

Section: A Creating Degrees Of Freedommentioning

confidence: 99%

How unitary cosmology generalizes thermodynamics and solves the inflationary entropy problem

Tegmark

2012

Phys. Rev. D

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We analyze cosmology assuming unitary quantum mechanics, using a tripartite partition into system, observer and environment degrees of freedom. This generalizes the second law of thermodynamics to "The system's entropy can't decrease unless it interacts with the observer, and it can't increase unless it interacts with the environment." The former follows from the quantum Bayes Theorem we derive. We show that because of the long-range entanglement created by cosmological inflation, the cosmic entropy decreases exponentially rather than linearly with the number of bits of information observed, so that a given observer can reduce entropy by much more than the amount of information her brain can store. Indeed, we argue that as long as inflation has occurred in a non-negligible fraction of the volume, almost all sentient observers will find themselves in a postinflationary low-entropy Hubble volume, and we humans have no reason to be surprised that we do so as well, which solves the so-called inflationary entropy problem. An arguably worse problem for unitary cosmology involves gamma-ray-burst constraints on the "Big Snap", a fourth cosmic doomsday scenario alongside the "Big Crunch", "Big Chill" and "Big Rip", where an increasingly granular nature of expanding space modifies our life-supporting laws of physics. Our tripartite framework also clarifies when the popular quantum gravity approximation Gµν ≈ 8πG Tµν is valid, and how problems with recent attempts to explain dark energy as gravitational backreaction from super-horizon scale fluctuations can be understood as a failure of this approximation.

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Section: A Creating Degrees Of Freedommentioning

confidence: 99%

How unitary cosmology generalizes thermodynamics and solves the inflationary entropy problem

Tegmark

2012

Phys. Rev. D

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“…A 22-rod + 2-posts arrangement has been found for the spoke cavities cryomodule of ESS (Figure 3b) [14][15][16]. The 22 rods are distributed on two individual cavities: 8 in the criss-cross "8-support" architecture, for each cavity being used to react lateral and vertical loads; 2 axial rods for each body; and 2 rods interconnecting the two cavities that have been used to control the relative and absolute axial alignment.…”

Section: The Cavity Architecture and Geometrymentioning

confidence: 99%

Literature Review of Suspension Systems for Superconducting Elements

Piacentini,

Dassa,

Perini

et al. 2023

Machines

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When designing suspension systems for superconducting elements, the primary challenge is to strike a balance between limiting the heat load to the cold mass and ensuring the proper mechanical resistance and/or stiffness of the system. This trade-off often leads engineers to choose from a limited set of materials and supporting architectures. The aim of this study is to provide an overview of the different overall designs. Scientific articles were searched within the Google Scholar database using advanced search operators to combine a defined set of keywords. Among the architectures found, the “multi-post” solution and the “8-support” solution are the two most commonly chosen classes. Additionally, a recurrent pattern for the supporting system of superconducting cavities has been identified. The choice of architecture can be correlated with the characteristics of the superconducting element being supported, such as its mass, length, and stiffness. Furthermore, the review provides a conceptual analysis of the possibility of extending these designs to the unconventional environment of rotating machines.

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“…European x-ray free electron laser-XFEL facility in Hamburg [4]), and for neutron spallation sources (e.g. European Spallation Source-ESS in Lund [5]). In fact, they have enabled the production of electron/proton pulses with unprecedented intensity, quality and temporal structure.…”

Section: Introductionmentioning

confidence: 99%

Enhanced radio-frequency performance of niobium films on copper substrates deposited by high power impulse magnetron sputtering

Arzeo

Avino

Pfeiffer

et al. 2022

Supercond. Sci. Technol.

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We present a study of radio frequency properties of niobium ﬁlms deposited on copper by two diﬀerent approaches based on High Power Impulse Magnetron Sputtering, namely with a DC voltage biased substrate and with bi-polar target voltage. Such approaches enable the synthesis of dense superconducting layers. The superconducting radio frequency losses of these ﬁlms are characterized as a function of the applied RF magnetic ﬁeld using a dedicated calorimetric method. We report on a signiﬁcant reduction of the Q-slope phenomenon and the residual surface resistance in the characterized ﬁlms, achieving similar values as those obtained on bulk niobium surfaces qualiﬁed with the same technique. Our results pave the way towards the realization of Nb/Cu coated accelerating cavities featuring a surface resistance 2-3 times lower than the state-of-the-art values at the working frequencies of 400 and 800 MHz, making this technology even more appealing for future particle accelerators and colliders.

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The ESS spoke cavity cryomodules

Cited by 7 publications

References 3 publications

How unitary cosmology generalizes thermodynamics and solves the inflationary entropy problem

How unitary cosmology generalizes thermodynamics and solves the inflationary entropy problem

Literature Review of Suspension Systems for Superconducting Elements

Enhanced radio-frequency performance of niobium films on copper substrates deposited by high power impulse magnetron sputtering

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