Cryogenic operation and testing of the extended LHC Prototype Magnet String

Bézaguet, A.; Casas‐Cubillos, J.; Guinaudeau, H.; Hilbert, B.; Lebrun, P.; Serio, L.; Suraci, A.; Weelderen, R. van

doi:10.1016/b978-008042688-4/50021-1

Cited by 9 publications

(3 citation statements)

References 4 publications

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“…Superconducting magnet cold masses are housed in horizontal cryostats [2] with several layers of heat interception and screening. Prototype full-scale models [3] have been built, tested and assembled into a test String [4,5] in order to validate nominal and accidental operational modes.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Thermal and Vacuum Transients on the LHC Prototype Magnet String

Cruikshank

Kos

Riddone

et al. 1997

Proceedings of the Sixteenth International Cryogenic Engineering Conference/International Cryogenic Materials Conference

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The prototype magnet string, described in a companion paper, is a full-scale working model of a 50-m length of the future Large Hadron Collider (LHC), CERN's new accelerator project, which will use high-field superconducting magnets operating below 2 K in superfluid helium. As such, it provides an excellent test bed for practising standard operating modes of LHC insulation vacuum and cryogenics, as well as for experimentally assessing accidental behaviour and failure modes, and thus verifying design calculations. We present experimental investigation of insulation vacuum pumpdown, magnet forced-flow cooldown and warmup, and evolution of residual vacuum pressures and temperatures in natural warmup, as well as catastrophic loss of insulation vacuum. In all these transient modes, experimental results are compared with simulated behaviour, using a non-linear, one-dimensional thermal model of the magnet string.

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Section: Introductionmentioning

confidence: 99%

Investigation of Thermal and Vacuum Transients on the LHC Prototype Magnet String

Cruikshank

Kos

Riddone

et al. 1997

Proceedings of the Sixteenth International Cryogenic Engineering Conference/International Cryogenic Materials Conference

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“…The remaining circuits are used for cool-down, 1.9 K temperature control, and cryostat heat intercepts. The string cryogenic system is described in detail in references 3,4 . Prior to their mounting in the string, each magnet has been quench-tested separately in standalone configuration 5 .…”

Section: The Prototype Magnet Stringmentioning

confidence: 99%

Thermohydraulics of quenches and helium recovery in the LHC prototype magnet strings

et al. 1998

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* LHC DivisionPresented at CHATS'97, San Francisco, USA 23-25 July 1997 Administrative Secretariat LHC Division CERN CH -1211 Geneva 23 Switzerland Geneva, 17 November 1997In 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. In 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.

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“…Each cool-down lasted 3 to 5 days depending on the limitations imposed on temperature gradients across individual magnets. Following a quench, automatic procedures took 6 to 12 hours to cool-down the magnets from approximately 30 K [3,4]. The temperature of the magnets was controlled by a Joule-Thomson valve with very stringent operational constraints (0.025 K control band) imposed by the superconducting magnets characteristics, the capacity of the cryogenic system, the variability of heat loads and the accuracy of instrumentation (± 0.01 K).…”

Section: String Operationmentioning

confidence: 99%

The LHC magnet string programme: status and future plans

Bordry

Casas‐Cubillos²,

Cruikshank³

et al.

Proceedings of the 1999 Particle Accelerator Conference (Cat. No.99CH36366)

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String 1, with one twin aperture quadrupole and three twin aperture 10-m dipoles (MB1, MB2 and MB3) powered in series and operating at 1.9 K, has recently been dismantled after four years of operation interrupted by technical stops and shutdowns for upgrading or exchanging equipment. Following the validation of the main LHC systems (cryogenics, magnet protection, vacuum, powering and energy extraction) the experimental programme was oriented towards the optimisation of the design and the observation of artificially induced fatigue effects. The design study for String 2 has been completed. This facility, which will be commissioned in December 2000, is composed of two LHC half-cells each consisting of one twin aperture quadrupole and three 15-m twin aperture dipoles. A cryogenic distribution line housing the supply and recovery headers runs parallel to the string of magnets. An electrical feedbox is used to power, with high temperature superconductor current leads, the circuits as in the regular part of an LHC arc. This paper reviews the experiments carried-out with String 1 and summarises the results obtained after more than 12800 hours of operation below 1.9 K and 172 quenches. It also describes the layout and the components of String 2 and explains the objectives pursued by its designers. STRING OPERATIONThe facility was operated between December 1994 [1] and December 1998. During this time, the magnets experienced 172 quenches. 144 were provoked by firing quench heaters. 70 quenches were above nominal current (12.4 kA). The magnets remained excited at nominal current for 314 hours [2]. Each cool-down lasted 3 to 5 days depending on the limitations imposed on temperature gradients across individual magnets. Following a quench, automatic procedures took 6 to 12 hours to cool-down the magnets from approximately 30 K [3,4]. The temperature of the magnets was controlled by a Joule-Thomson valve with very stringent operational constraints (0.025 K control band) imposed by the superconducting magnets characteristics, the capacity of the cryogenic system, the variability of heat loads and the accuracy of instrumentation (± 0.01 K).Model-based predictive control (MBPC) algorithms were investigated in order to obtain a narrower control band compared to standard PID control loops [5,6]. Preliminary results were encouraging but the temperature operational range was limited because only linear approximations of the process were used. Future developments are the implementation of non-linear models into the MBPC controller. Before being able to power the magnets an in-situ calibration of the temperature sensors was necessary. The observed reproducibility between sensors was better than 0.01 K and no degradation was measurable during the 4 years of operation. The String was controlled and monitored [7] from a dedicated control room but could be controlled from any remote terminal with appropriate privileges. Over 600 process variables were archived during the lifetime of the String every second and, transients on volt...

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Cryogenic operation and testing of the extended LHC Prototype Magnet String

Cited by 9 publications

References 4 publications

Investigation of Thermal and Vacuum Transients on the LHC Prototype Magnet String

Investigation of Thermal and Vacuum Transients on the LHC Prototype Magnet String

Thermohydraulics of quenches and helium recovery in the LHC prototype magnet strings

The LHC magnet string programme: status and future plans

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