Heat Transfer from Insulated Rutherford Type Cables Immersed in Pressurized He II

Abstract-In superconducting magnets operating at high heat loads as the ones for interaction region of particle colliders or for fast cycling synchrotrons, the limited heat transfer capability of state-of-the-art electrical insulation may constitute a heavy limitation to performance. In the LHC main magnets, Nb-Ti epoxy-free insulation, composed of polyimide tapes, has proved to be permeable to superfluid helium, however the heat flux is rather limited.After a review of the standard insulation scheme for Nb-Ti and of the associated heat transfer mechanisms, we show the existence of a large margin available to improve insulation permeability. We propose a possible way to profit of such a margin in order to increase significantly the maximum heat flux drainable from an all polyimide insulated Nb-Ti coil, as it is used in modern accelerator magnets.

Section: Heat Transfer Modelmentioning

confidence: 98%

Cable Insulation Scheme to Improve Heat Transfer to Superfluid Helium in Nb-Ti Accelerator Magnets

China

Tommasini

2008

“…Although the conductor surface was machined to reproduce the external cable surface, helium could not penetrate inside the conductor; therefore the cable cross-section below the λ temperature T λ was not isothermal. The setup developed at KEK to qualify the LHC MQXA interaction region quadrupoles made use of resistive cables with the same geometry of the superconducting ones, thus allowing superfluid helium (He II) to fill the interstices among strands [12] [13]. Heat transfer studies carried out at CERN were performed in a first stage on a segment of a superconducting LHC dipole coil [14].…”

Section: T 5oraa-03mentioning

confidence: 99%

“…The loss rate was 1.63·10 12 protons·s -1 , obtained with collimation settings (TCP7 at 6.1 σ, TCS7 at 10.1 σ [37]) that were more open than during standard operation, thus creating higher losses in the magnets. The heat deposit, averaged over the inner layer cable, was calculated to be 50 mW/cm 3 [35] [36].…”

Section: Quench Limitsmentioning

confidence: 99%

Deduction of Steady-State Cable Quench Limits for Various Electrical Insulation Schemes With Application to LHC and HL-LHC Magnets

Granieri

Weelderen

2014

Abstract-Undesired quenches of superconducting magnets can be a limiting factor for the operation of the LHC accelerator, both for its forthcoming exploitation at full energy as well as for its future upgrades. An accurate knowledge of the quench limit, the maximum amount of heat deposit the magnets can withstand, is required to be able to prevent beam induced quenches.In this paper we provide an overview of the heat extraction through the multitude of cable insulation schemes used in particle accelerators in the past 20 years and foreseen for the coming years. Based on the relevant heat transfer measurements, we deduce steady-state cable quench limits both for the LHC Nb-Ti magnets and for the future HL-LHC Nb 3 Sn ones. We provide them for different operating conditions and different locations within the coil.  Index Terms-Electrical insulation, heat transfer, superconducting high field magnets, LHC, LHC upgrade, Nb 3 Sn, Nb-Ti, quench limit.

“…The experimental procedure was reported [9], brief experimentation describes here. Technical parameters for the cable and insulation, and curing parameters for the specimens are summarized in TableI.…”

Section: A Experimental Setup and Measurementmentioning

confidence: 99%

Heat transfer characteristics of Rutherford-type superconducting cables in pressurized He II

Kimura

Yamamoto²,

Shintomi³

et al. 1999

Self Cite

The heating induced by beam-loss i n superconducting cables must be absorbed by pressurized He I1 through the cable insulation in o peration of the LHC accelerator superconducting magnets. As a fundamental study, the heat transfer characteristics through the insulated cable to t h e pressurized He I1 were measured in case of t h e "Rutherford" type compacted strand cables. T h i s report describes the experimental results and discusses possible heat transfer models.