Using LHC as injector and possible uses of HERA magnets/coils

This workshop discusses the various aspects of a high energy version of the LHC in the LHC tunnel, the basic assumption being that the LHC will be decommissioned. The possibilities to recycle LHC and the already stopped HERA are discussed in this paper.Comment: 8 pages, contribution to the EuCARD-AccNet-EuroLumi Workshop: The High-Energy Large Hadron Collider, Malta, 14 -- 16 Oct 2010; CERN Yellow Report CERN-2011-003, pp. 116-12

Electronic Systems for the Protection of Superconducting Devices in the LHC

The Large Hadron Collider LHC [1] incorporates an unprecedented amount of superconducting components: magnets, bus-bars, and current leads. Most of them require active protection in case of a transition from the superconducting to the resistive state, the so-called quench. The electronic systems ensuring the reliable quench detection and further protection of these devices have been developed and produced over the last years and are currently being put into operatio

Extending the Use of HTS to Feeders in Superconducting Magnet Systems

Following the successful adoption of high temperature superconductors (HTS) in over a thousand current leads that will feed 3 MA from warm to cold in the Large Hadron Collider (LHC), the use of HTS has been generally accepted as suitable technology for the design of efficient leads feeding cryo-magnets. We now consider the extension of the technology to the interconnection of strings of superconducting magnets and their connection to feed-boxes through which the excitation current is fed. It is proposed to use HTS material for this application instead of low-temperature superconductor or normal-conducting material. The implications of adopting this technology are discussed with regard to the choice of materials, highlighting the differences with more conventional schemes. Examples are given of how this approach could be applied to the consolidation and upgrade of the LHC

Results from Commissioning of the Energy Extraction Facilities of the LHC Machine

The risk of damage to the superconducting magnets, bus bars and current leads of the LHC machine in case of a resistive transition (quench) is being minimized by adequate protection. The protection is based on early quench detection, bypassing the quenching magnets by cold diodes, energy density dilution in the quenching magnets using heaters and, eventually, energy extraction. For two hundred and twenty-six LHC circuits (600 A and 13 kA) extraction of the stored magnetic energy to external dump resistors was required. All these systems are now installed in the machine and the final hardware commissioning has been undertaken. After a short description of the topology and definitive features, layouts and parameters of these systems the paper will focus on the results from their successful commissioning and an analysis of the system performance

Commissioning of the LHC Current Leads

The powering of the LHC superconducting magnets relies on more than 3000 current leads transporting the current to/from the cryogenic environment and rated at currents ranging from 60 A to 13000 A. The design of these leads, about 1000 of which are based on high temperature superconducting material, was entirely done at CERN, where prototype assemblies were also assembled and tested, while the series production and testing was done in external laboratories and companies on the basis of build-to-print specifications. This report summarizes the results of the tests performed during the commissioning of the LHC machine, when the leads underwent the thermal and electrical cycles necessary for the powering of the LHC superconducting circuit

Diffusion due to the Beam-Beam Interaction and Fluctuating Fields in Hadron Colliders

Random fluctuations in the tune, beam offsets and beam size in the presence of the beam-beam interaction are shown to lead to significant particle diffusion and emittance growth in hadron colliders. We find that far from resonances high frequency noise causes the most diffusion while near resonances low frequency noise is responsible for the large emittance growth observed. Comparison of different fluctuations shows that offset fluctuations between the beams causes the largest diffusion for particles in the beam core.Comment: 5 pages, 3 postscript figure

Towards the Design of Power Switches Utilizing HTS Material

Conventional superconducting switches for power applications, which operate at liquid helium temperature, generally utilize Nb-Ti superconductor in a cupro-nickel matrix. For superconducting circuits based on High Temperature Superconductors (HTS) that work at higher temperatures, the associated superconducting switches must also be based on HTS. This paper addresses the issues concerning the requirements and the appropriate design of HTS switches, including approaches to fast triggering