Assessment of thermal loads in the CERN SPS crab cavities cryomodule11Work supported by the European Union HL-LHC Project and by US DOE through Brookhaven Science Associates LLC under contract No. DE-AC02-98CH10886 and the US LHC Accelerator Research Program (LARP). Research supported by the HL-LHC project.

F Carra,S Verdú-Andrés,J Apeland,O Capatina,T Capelli,R Calaga,C Zanoni

doi:10.1088/1742-6596/874/1/012005

Abstract

As a part of the HL-LHC upgrade, a cryomodule is designed to host two crab cavities for a first test with protons in the SPS machine. The evaluation of the cryomodule heat loads is essential to dimension the cryogenic infrastructure of the system. The current design features two cryogenic circuits. The first circuit adopts superfluid helium at 2 K to maintain the cavities in the superconducting state. The second circuit, based on helium gas at a temperature between 50 K and 70 K, is connected to the thermal screen, also serving as heat intercept for all the interfaces between the cold mass and the external environment. An overview of the heat loads to both circuits, and the combined numerical and analytical estimations, is presented. The heat load of each element is detailed for the static and dynamic scenarios, with considerations on the design choices for the thermal optimization of the most critical components.

Highlights

Introduction and heat budgetOne key element of the LHC upgrade, known as HL-LHC, is represented by the adoption of a crab-crossing scheme, provided by a set of compact SRF crab cavities [1]
The evaluation of the cryomodule heat loads is essential to dimension the cryogenic infrastructure of the system
The cavities are cooled with superfluid helium at 2 K, and a second circuit with helium gas, at a temperature between 50 K and 70 K, is connected to the thermal screen, serving as heat intercept for all the elements connecting the cold mass and the external environment

Summary

K 80 K

2. Supports, tuning system and cold/warm transitions These elements are not traversed by electrical currents and contribute only to the static losses of the system. Supports, tuning system and cold/warm transitions These elements are not traversed by electrical currents and contribute only to the static losses of the system Their thermal design keeps into account the heat flowing by conduction from the thermal screen circuit to the helium tank (80 K – 2 K), and exchanged between the external ambient and the thermal screen (300 K – 80 K). The contribution of thermal radiation was investigated and found to be negligible; the problem is solved analytically, for each element, with the Fourier’s equation: Q2K

A L-Lint

Findings

Conclusions