engLebrun, PSuperfluid helium as a technical coolantAccelerators and Storage RingsLHC-Project-Report-125CERN-LHC-Project-Report-125The characteristics of superfluid helium as a technical coolant, which derive from its specific transport properties, are presented with particular reference to the working area in the phase diagram (saturated or pressurised helium II). We then review the principles and scaling laws of heat transport by equivalent conduction and by forced convection in pressurised helium II, thus revealing intrinsic limitations as well as technological shortcomings of these cooling methods. Once properly implemented, two-phase flow of saturated helium II presents overwhelming advantages over the previous solutions, which dictated its choice for cooling below 1.9 K the long strings of superconducting magnets in the Large Hadron Collider (LHC), a 26.7 km circumference particle collider now under construction at CERN, the European Laboratory for Particle Physics near Geneva (Switzerland). We report on recent results from the ongoing research and development programme conducted on thermohydraulics of two-phase saturated helium II flows, and on the validation of design choices for the LHC cooling system.1997-07-17http://cds.cern.ch/record/330851http://cds.cern.ch/record/330851oai:cds.cern.ch:330851revised version submitted on 2004-08-19 14:20:41 doi:10.1016/S0011-2275(98)00015-0engChorowski, MLebrun, PSerio, LVan Weelderen, RThermohydraulics of Quenches and Helium Recovery in the LHC Magnet StringsAccelerators and Storage RingsLHC-Project-Report-154CERN-LHC-Project-Report-154In preparation for the Large Hadron Collider project, a 42.5 m-long prototype superconducting magnet string, representing a half-cell of the machine lattice, has been built and operated. A series of tests was performed to assess the thermohydraulics of resistive transitions (quenches) of the superconducting magnets. These measurements provide the necessary foundation for describing the observed evolution of the helium in the cold mass and formulating a mathematical model based on energy conservation. The evolution of helium after a quench simulated with the model reproduces the observations. We then extend the simulations to a full LHC cell, and finally analyse the recovery of helium discharged from the cold mass.1997-11-17http://cds.cern.ch/record/34109410.1016/S0011-2275(98)00015-0http://cds.cern.ch/record/341094oai:cds.cern.ch:341094 doi:10.1109/20.717687engRamberger, SRussenschuck, StephanGenetic Algorithms with Niching for Conceptual Design StudiesAccelerators and Storage RingsLHC-Project-Report-155CERN-LHC-Project-Report-155The paper describes the use of genetic algorithms with the concept of niching for the conceptual design of superconducting magnets for the Large Hadron Collider, LHC at CERN. The method provides the designer with a number of possible solutions which can then be further optimized for field quality and manufacturability. Two 6 block dipole coils were found and proved to have advantages compared to the standard 5 block version.1997-11-19http://cds.cern.ch/record/34049010.1109/20.717687http://cds.cern.ch/record/340490oai:cds.cern.ch:340490revised version submitted on 2004-08-19 15:48:17 engHerleb, URiege, HExperiments on Ion Beam Space-Charge Neutralization with Pulsed Electron BeamsAccelerators and Storage RingsCERN-LHC-97-011-DLOSpace-charge neutralization of heavy ion beams with electron beam pulses generated by electron guns incorporating ferroelectric cathodes has been experimentally investigated. Several experiments are described, the results of which prove that the intensity of selected ion beam parts with defined charge states generated in a laser ion source can be increased by an order of magnitude. For elevated charge states the intensity amplification is more significant than for low charge states. A charge enhancement factor of four has been achieved by neutralization with pulsed electron beams for Al7+ ions generated from an aluminium target.1997-11-25http://cds.cern.ch/record/341127http://cds.cern.ch/record/341127oai:cds.cern.ch:341127 engGourber, J PStatus of the LHCAccelerators and Storage RingsLHC-Project-Report-167CERN-LHC-Project-Report-167Since the approval of the Large Hadron Collider (LHC) by the CERN Council in December 1994, considerable progress has been made in the assessment of the beam parameters and the refining of the design of the machine components and experimental areas. Thanks to the strong support from a number of countries outside the Member States, the machine will be constructed in one single stage with first physics in 2005. The first large calls for tenders are being launched. The status of the project and the future plans are presented.1998-02-27http://cds.cern.ch/record/347898http://cds.cern.ch/record/347898oai:cds.cern.ch:347898 engRussenschuck, StephanSuperconducting Magnets for the LHC: Conception, Optimization and Inverse Problem SolvingAccelerators and Storage RingsLHC-Project-Report-142CERN-LHC-Project-Report-142The Large Hadron Collider (LHC), approved by the CERN Council in December 1994, is a 7+7 TeV proton accelerator-collider, to be installed in the existing 27 km long LEP tunnel. The main technological challenges of the machine are the superconducting magnets, in total over 8'000 units immersed in superfluid helium, and the very large cryogenic system, which maintains the entire string of cryomagnets at its working temperature below 2 K. The paper gives an overview on the design process of the superconducting magnets where mathematical optimization techniques are applied. For the concept phase genetic optimization algorithms are used, followed by deterministic methods for the coil and iron cross-section optimization. Inverse problem solving is finally applied to trace manufacturing errors.1997-10-15http://cds.cern.ch/record/344864http://cds.cern.ch/record/344864oai:cds.cern.ch:344864