Reliability of the quench protection system for the LHC superconducting elements

Fernandez, A. Vergara; Rodriguez-Mateos, F.

doi:10.1016/j.nima.2004.01.081

Cited by 8 publications

(5 citation statements)

References 28 publications

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“…Since this test implies the discharge of the quench heater power supplies, it can only be performed when the magnets are cold and not powered. When Quench Tests are performed monthly and repairs are carried out before re-powering the circuits (see below), the probability of missing a quench during 20 years of operation is below 1% [36]. The expected number of false quenches is around 10 per year.…”

Section: Quench Detectorsmentioning

confidence: 99%

LHC Machine

Evans¹,

Bryant²

2008

J. Inst.

1,820

1,344

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2008 JINST 3 S08001 9.3.1 The VME and PC Front End Computers 9.3.2 The PLCs 9.3.3 The supported fieldbuses 9.3.4 The WorldFIP fieldbus 9.3.5 The Profibus fieldbus 9.4 Servers and operator consoles 9.5 Machine timing and UTC 9.5.1 Central beam and cycle management 9.5.2 Timing generation, transmission and reception 9.5.3 UTC for LHC time stamping 9.5.4 UTC generation, transmission and reception 9.5.5 NTP time protocol 9.6 Data management 9.6.1 Offline and online data repositories 9.6.2 Electrical circuits 9.6.3 Control system configuration 9.7 Communication and software frameworks 9.7.1 FEC software framework 9.7.2 Controls Middleware 9.7.3 Device access model 9.7.4 Messaging model 9.7.5 The J2EE framework for machine control 9.7.6 The UNICOS framework for industrial controls 9.7.7 The UNICOS object model 9.8 Control room software 9.8.1 Software for LHC beam operation 9.8.2 Software requirements 9.8.3 The software development process 9.8.4 Software for LHC Industrial Systems 9.9 Services for operations 9.9.1 Analogue signals transmission 9.9.2 Alarms 9.9.3 Logging 9.9.4 Post mortem 10 Beam dumping 10.1 System and main parameters 13 LHC as an ion collider 13.1 LHC parameters for lead ions 13.1.1 Nominal ion scheme 13.1.2 Early ion scheme 13.2 Orbits and optical configurations for heavy ions 13.3 Longitudinal dynamics 13.4 Effects of nuclear interactions on the LHC and its beams 13.5 Intra-beam scattering 13.6 Synchrotron radiation from lead ions LHC machine acronyms Bibliography-vi-2008 JINST 3 S08001 Chapter 1 2008 JINST 3 S08001 2.2.7 Collective beam instabilities The interaction of the charged particles in each beam with each other via electromagnetic fields and the conducting boundaries of the vacuum system can result in collective beam instabilities. Generally speaking, the collective effects are a function of the vacuum system geometry and its surface properties. They are usually proportional to the beam currents and can therefore limit the maximum attainable beam intensities. 2.2.8 Luminosity lifetime The luminosity in the LHC is not constant over a physics run, but decays due to the degradation of intensities and emittances of the circulating beams. The main cause of the luminosity decay during nominal LHC operation is the beam loss from collisions. The initial decay time of the bunch intensity, due to this effect, is:

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Section: Quench Detectorsmentioning

confidence: 99%

LHC Machine

Evans¹,

Bryant²

2008

J. Inst.

1,820

1,344

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“…Different topological states are modelled by changing the exponent n in the specific heat term in equation (3). For each topological state a 'phase boundary' is constructed as a function of W , T h and T q ; see figure 4.…”

Section: Methods and Resultsmentioning

confidence: 99%

“…More specifically, the nodal superconductor with the lowest exponent will be preferred as it will have the highest specific heat. We can therefore study the effect different topological states can have on quench behaviour by altering the exponent n in equation (3). In this proof-of-concept work we do not consider the effect of pinning.…”

Section: Modelmentioning

confidence: 99%

Can Topological Transitions be Exploited to Engineer Intrinsically Quench-Resistant Wires?

Whittlesea

Quintanilla

Annett

et al. 2018

IEEE Trans. Appl. Supercond.

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We investigate whether by synthesising superconductors that are tuned to a topological, node-reconstruction transition point we could create superconducting wires that are intrinsically resilient to quenches. Recent work shows that the exponent characterising the temperature dependence of the specific heat of a nodal superconductor is lowered over a region of the phase diagram near topological transitions where nodal lines form or reconnect. Our idea is that the resulting enhancement of the low-temperature specific heat could have potential application in the prevention of superconductor quenches. We perform numerical simulations of a simplified superconductor quench model. Results show that decreasing the specific heat exponent can prevent a quench from occurring and improve quench resilience, though in our simple model the effects are small. Further work will be necessary to establish the practical feasibility of this approach.

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“…It is noteworthy that many facilities have considered reliability in safety analyses and in machine protection systems in order to avoid huge machine damage and large shutdown periods like in LHC [38,39]. Some of the tools used in these analyses can be similar to those used in RAMI, but the goals and results of the studies can be different.…”

Section: Rami Analyses In Particle Acceleratorsmentioning

confidence: 99%

“…Taking into account the IFMIF maintenance plan described in Chapter 1, the accelerator scheduled operation time is around 8,208 hours per year. Compared with other accelerators (PSI 5,600 h, SNS 4,900 h, LANSCE 3,300 h [89] and LHC 5,110 h [38]), IFMIF's operation/maintenance plan is highly exigent. Operation and maintenance plans are key aspects of availability estimation analyses.…”

Section: Operation and Maintenance Plans In Other Facilitiesmentioning

confidence: 99%

IFMIF accelerator facility RAMI analyses in the engineering design phase

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The planned International Fusion Materials Irradiation Facility (IFMIF) has the mission to test and qualify materials for future fusion reactors. IFMIF will employ the deuteron-lithium stripping reaction to irradiate the test samples with a high-energy neutron flux. IFMIF will consist mainly of two linear deuteron accelerators, a liquid lithium loop and a test cell. Accelerated deuterons will collide with the lithium producing a high-energy neutron flux that will irradiate the material samples in the test cell. A timely and relevant fusion neutron source is essential in the path towards DEMO and future fusion power plants. For this reason, IFMIF is required to have high availability to obtain a fusion materials database to find suitable materials for DEMO design within the anticipated timeline. RAMI (Reliability Availability Maintainability Inspectability) analyses are being performed in the very early stages of design to meet such requirements. The IFMIF accelerator facility is composed of two independent linear accelerators, each of which produces a 40 MeV, 125 mA deuteron beam in a continuous wave mode at 175 MHz. These beam characteristics pose several unprecedented challenges: the highest beam intensity, the highest space charge, the highest beam power and the longest RFQ (Radio Frequency Quadrupole). As a result of these challenges, many design characteristics are counter to high-availability performance: the design is reluctant to accept failures, machine protection systems are likely to stop the beam undesirably, cryogenic components require long periods for maintenance, and activation of components complicates maintenance activities. These design difficulties, together with the high availability requirements and the demanding scheduled operational periods, make RAMI analysis an essential tool in the engineering design phase. These studies were performed in collaboration with system designers, enabling the creation of RAMI models that reflect current accelerator design. This feedback has been of the utmost importance to propose plausible design modifications in order to improve the availability performance of the machine. Parallel activity on the design and construction of the Linear IFMIF Prototype Accelerator (LIPAc) provided the detailed design information needed to conduct these studies properly. An iterative process was followed to match IFMIF design and availability studies. These iterations made it possible to include recommendations and design change proposals coming from the RAMI analyses into the accelerator reference design. Iterations consist of gathering information from the design, creating or updating the RAMI models, obtaining and analyzing results, and proposing ways to improve the design. Three different approaches were carried out in the iterative process. First, a comparison with other similar facilities was performed. Second, an individual fault tree analysis was developed for each system of the accelerator. Finally, a Monte Carlo simulation was performed for the whole accelerator facility considering synergies between systems. These approaches make it possible to go from detailed hardware availability analyses to global accelerator performance, to identify weak design points, and to propose design alternatives as well as foresee IFMIF performance, maintenance and operation characteristics. The IFMIF accelerator facility design was analyzed from the RAMI point of view, estimating its future availability and guiding the design towards a high reliability and availability performance. In order to achieve the high-availability requirements several design changes have already been included in the accelerator reference design whereas other important design modifications have been proposed and will be further analyzed in future design phases.

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Reliability of the quench protection system for the LHC superconducting elements

Cited by 8 publications

References 28 publications

LHC Machine

LHC Machine

Can Topological Transitions be Exploited to Engineer Intrinsically Quench-Resistant Wires?

IFMIF accelerator facility RAMI analyses in the engineering design phase

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