Powering and Machine Protection of the Superconducting LHC Accelerator

A very large number of magnets, both superconducting and conventional copper conductor magnets, are installed in the LHC (Large Hadron Collider) for the guidance of the two proton beams around the circumference. In total, the LHC counts 1614 different electrical circuits with 1712 power converters for DC powering of the superconducting and normal conducting magnets. Besides the electrical circuits connecting main magnets for bending and focusing of the two counter-rotating beams, the demanding requirements on the quality of the magnetic fields require a large number of circuits for corrector magnets distributed around the circumference. In total, more than 10000 magnets will need to be connected to the power converters via a large inventory of electrical components such as normal conducting cables and tubes, energy extraction systems, current feedthroughs and superconducting busbars. Depending on the complexity and importance of these electrical circuits and their components, various systems will interact for their powering and protection. For example the stored energy in each of the main dipole circuits amounts to 1.2 GJ and requires strict but intelligent protection measures to avoid damage to valuable accelerator equipment. Due to the unprecedented complexity of the LHC powering system the equipment protection demands a coherent description of the circuits within the LHC Reference Database. This description, which forms a vital basis of the present thesis, will provide reliable and important information to various clients. Generating input files for optics programs such as MAD automatically from the database will support the design and optimization process of the accelerator. Later on, the installation process will be supported with data for the interconnections to be performed between the cryogenic assemblies in the LHC tunnel and data will also be used for quality assurance tests. Protection of the installed superconducting equipment is assured by the powering interlock controller, using newly developed, flexible and intelligent protection mechanisms. During commissioning and operation, the information in the database about the electrical installations is used by the interlock controllers to automatically configure its software that will be running in 36 different locations of the LHC tunnel. Depending on properties of the different electrical circuits such as the stored magnetic energies, maximum current ratings, natural time constants and the importance for beam operation, advanced protection mechanisms are configurable and intertwine for the protection of equipment. This is possible due to a flexible and modular approach for the hardware and software to be deployed for the powering interlock controller. Depending on the number of electrical circuits and their types, various developed hardware modules can be installed in the racks of the powering interlock controller, while a unique program will be configured according to the installed hardware.