Summary of the LHC Workshop on Dynamic Effects and their Control

A brief overview is given of the discussions and recommendations formulated during the ³LHC Workshop on Dynamic Effects and their Control². The workshop took place at CERN from 5 to 7 February 1997 in order to discuss the required performance for the control of the LHC beams and the accuracy, reproducibility and stability of various key equipment in the presence of the expected dynamic effects of the LHC superconducting magnets

Electrical powering strategy of LHC: first design study

Superconducting accelerators, and in particular the LHC, require detailed analysis of the electrical powering due to the integrated nature of these machines. The situation is made more difficult in LHC where the maximum use needs to be made of the existing infra-structure, notably the AC electrical distribution and the underground excavations of LEP. This, coupled with the dynamic performance of the main dipole magnets, the quench protection requirements and the needs of the accelerator physics, have meant that new powering techniques, as well as tighter power converter perform-ance specifications, will be required. A description of the powering system of LHC is given along with the reasons for adopting certain solutions. The static and dynamic requirements of the machine are also discussed and the first ideas for solving some of these problems are presented. In all the LHC will use about 1500 power converters able to supply approximately 1750 kA in total. Some of the on-going studies to achieve a better optimisation of the powering system are also discussed

Update on the powering strategy of LHC

Over the last two years the powering strategy of the Large Hadron Collider (LHC) has undergone a considerable evolution. This was not only motivated by new requirements but more importantly by a quest to reduce costs and improve operational reliability and flexibility. In order to achieve this, despite an increase in complexity, novel modifications to the strategy and hardware have been proposed both on the warm and cold sides of the machine. During this process the requirements of the accelerator physics have been clarified and met while working within the boundary conditions imposed by the utilisation of the existing CERN infrastructure. After a brief review of the present powering strategy which needs to produce and supply 2MA dc in 1800 circuits, more detailed descriptions will be given of the changes implemented in order to achieve a more rational overall system. Some performance issues of the powering system will also be discussed

Summary of the LHC Controls and Operations Forum held at CERN on 1-2 December 1999

The LHC Controls-Operations Forum in December attempted to identify the challenges of running the LHC and the implications for controls and equipment. An outline of the forum, its objectives, summaries of the various sessions, conclusions and some recommendations are presented. It is anticipated that this information will act as input into current and future development

Update of the LHC Arc Cryostat Systems Layouts and Integration

Since the LHC Conceptual Design report's publication in October 1995 [1], and subsequent evolutions [2], the LHC Arc Cryostat System has undergone recently a number of significant changes, dictated by the natural evolution of the project. Most noteworthy are the recent decisions to route the large number of auxiliary circuits feeding the arc corrector magnets in a separate tube placed inside the cryostat with connections to the magnets every half-cell. Further decisions concern simplification of the baseline vacuum and cryogenic sectorization, the finalization of the design of the arc cryogenic modules and the layout of the arc electrical distribution feedboxes. The most recent features of the highly intricate cryogenics, magnetic, vacuum and electrical distribution systems of the LHC are presente

The Protection System for the Superconducting Elements of the Large Hadron Collider at CERN

The protection system for the superconducting elements of the Large Hadron Collider (LHC) [1] at the European Laboratory for Particle Physics (CERN), and its associated equipment are presented: quench detectors, cold diodes, quench heaters and related power supplies, extraction resistors and associated current breakers. Features such as radiation resistance, redundancy and required reliability are discussed

Dynamic Effects and their Control at the LHC

Tune, chromaticity and orbit of the LHC beams have to be precisely controlled by synchronising the magnetic field of quadrupole, sextupole and corrector magnets.This is a challenging task for an accelerator using superconducting magnets, whose field and field errors will have large dynamic effects.The accelerator physics requirements are tight due to the limited dynamic aperture and the large energy stored in the beams.The power converters need to be programmed in order to generate the magnetic functions with defined tolerances. During the injection process and the energy ramp the magnetic performance cannot be predicted with sufficient accuracy, and therefore real-time feedback systems based on magnetic measurements and beam observations are proposed. Beam measurements are used to determine a correction factor for some of the power converters. From magnetic measurements the excitation of small magnets to compensate the sextupolar (b3) and decapolar (b5) field components in the dipole magnets will be derived. To meet these requirements a deterministic control system is envisaged

The LHC Prototype Full-Cell: Design Study

As a continuation of the experimental program carried-out with String 1, project management decided toward the end of 1995 to construct an LHC prototype Full-Cell, also known as String 2. The present document reports on the outcome of the one-year design effort by the community of specialists contributing to the LHC Prototype Full-Cell: it informs specialists on the boundary areas with other syste ms and conveys to the general public a description of the facility