Geometry and Alignment Requirements for the LHC Main Dipole

The 15 m long LHC superconducting dipole magnets, which contain two beam channels in a common mechanical structure, produce a magnetic field of 8.3 T required to deflect protons with 7 TeV/c momentum along a circular trajectory in the already existing LEP tunnel. The dipoles are bent in their horizontal plane to provide the largest possible mechanical aperture to the circulating beam. This paper describes the theoretical geometry of the dipole cold mass and the alignment requirements, which are imposed to satisfy the demands of LHC machine operation. A short description of the measuring and alignment procedures and of the measuring instruments is given. Results of a small series of prototype cold masses are presented and discussed

Influence of geometrical parameters on the flexural rigidity of the LHC dipole cold mass assembly

In order to predict the mechanical behavior of the LHC dipole cold mass in situations such as handling, transport and cool down, a number of important structural parameters are required. The dipole's flexural rigidity determines entirely the mechanical elastic behavior of the cold mass. Therefore, models of a bent cold mass were created to calculate its rigidity. This paper presents a simplified parametric finite element model, created to study the deflection of the cold mass in different situations and supporting conditions. The sensitivity of the models to the supporting conditions is computed. To provide the finite element and the analytical models with input, the deflection of the cold mass under discrete loads in normal condition and then 90-degrees rotated were measured with a laser tracker. By comparing models with measurements, the vertical and transversal rigidity of the cold mass assembly are determined. Additionally, the paper reports on the plastic behavior of the cold mass assembly in the range of the deformations that are needed to correct cold masses that result, after final welding of the outer skin, with unacceptable sagitta

Statistical Studies of the Robustness of the LHC Main Dipole Mechanical Structure

This paper describes two methods used to study the effect of the tolerances of the components on the structure of the LHC main dipole. The first method, called semi-statistical, is useful for the study of the effect of single different parameters and allows the determination of the acceptable variance of the dimensions of magnet components. The second one, fully statistical, allows the study of the combined effect of many parameters. The use of these two methods allowed to evaluate with good confidence the robustness of two different dipole cross-section designs, featuring austenitic and aluminium alloy collars, respectively

FEM Computations Concerning the Effect of Friction in Two LHC Main Dipole Structures

The mechanical behaviour of a dipole structure is considered when also friction is taken into account, studying its effect on different components and in different conditions. In particular the difference in behavior between a structure with aluminium collars and one with austenitic steel ones was studied

The LHC Dipole Geometry as Built in Industry

The LHC dipoles magnets are produced in 5 industrial production sites in Europe. The production is well underway and more than half of the total quantity has been delivered to CERN. One of the important characteristics of the dipole magnets is their geometry. To achieve the requested mechanical tolerances on the magnets, which are 15 m long and have a 28 t mass, the final assembly operations includes precise optical measurements. To ensure the good quality and high production rate, the final assembly procedure has been automated as much as possible. The authors report here about the assembly procedure, the features of the software that guides the optical measurements (and consequently the assembly operations) and the results obtained on the geometry in the different sites

Mechanical Design of the SMC (Short Model Coil) Dipole Magnet

The Short Model Coil (SMC) working group was set in February 2007 within the Next European Dipole (NED) program, in order to develop a short-scale model of a Nb$_{3}$Sn dipole magnet. The SMC group comprises four laboratories: CERN/TE-MSC group (CH), CEA/IRFU (FR), RAL (UK) and LBNL (US). The SMC magnet was originally conceived to reach a peak field of about 13 T on conductor, using a 2500 A/mm2 Powder-In-Tube (PIT) strand. The aim of this magnet device is to study the degradation of the magnetic properties of the Nb$_{3}$Sn cable, by applying different level of pre-stress. To fully satisfy this purpose, a versatile and easy-to-assemble structure has to be realized. The design of the SMC magnet has been developed from an existing dipole magnet, the SD01, designed, built and tested at LBNL with support from CEA. In this paper we will describe the mechanical optimization of the dipole, starting from a conceptual configuration based on a former magnetic analysis. Two and three-dimensional Finite Element Method (FEM) models have been implemented in ANSYS™ and in CAST3M, aiming at setting the mechanical parameters of the dipole magnet structure, thus fulfilling the design constraints imposed by the materials

Geometric and Magnetic Axes of the LHC Dipole

The 15-m long superconducting dipoles of the Large Hadron Collider (LHC) with two-in-one design are curved by about 5 mrad to follow the beam trajectory. They are supported on three cold feet to minimise the vertical sagitta induced by their 35 tonnes weight. The cold masses contain at both ends local multipolar correctors to compensate for the detrimental effect of persistent current during injection. We discuss how we measure and control the geometrical shape of the cold mass and the alignment of the associated correctors and how we identify the magnetic axis of the field-shape harmonics with respect to the expected beam reference orbit. We present results relative to prototype dipoles obtained both at room temperature and in operational conditions at 1.9 K

Od Redakcji

JAROSŁAW ŁAWSKI – prof. zw. dr hab., pracownik Uniwersytetu w Białymstoku; badacz wyobraźni poetyckiej, twórca i kierownik Katedry Badań Filologicznych „Wschód – Zachód” w Instytucie Filologii Polskiej UwB; dziekan Wydziału Filologicznego. Zainteresowania badawcze: faustyzm i bizantynizm w literaturze polskiej, interpretacje Romantyzmu, Młoda Polska, polsko-wschodniosłowiańskie związki kulturowo oraz Czesław Miłosz. Redaktor naczelny Naukowych Serii Wydawniczych „Czarny Romantyzm”, „Przełomy/Pogranicza” oraz „Colloquia Orientalia Bialostocensia”. Autor książek, w tym: Wyobraźnia lucyferyczna. Szkice o poemacie Tadeusza Micińskiego „Niedokonany. Kuszenie Chrystusa Pana na pustyni” (Białystok 1995) oraz Mickiewicz – Mit – Historia. Studia (Białystok 2010). Ostatnio wydał: Miłosz: „Kroniki” istnienia. Sylwy interpretacyjne (Białystok 2014). Członek Komitetu Nauk o Literaturze PAN; członek korespondent Polskiej Akademii Umiejętności.MARCIN BAJKO – dr, adiunkt w Katedrze Badań Filologicznych „Wschód – Zachód” na Wydziale Filologicznym Uniwersytetu w Białymstoku. Zainteresowania badawcze: pisarstwo Tadeusza Micińskiego w kontekście literatury romantycznej i młodopolskiej; twórczość Juliusza Słowackiego, Seweryna Goszczyńskiego, „czarny romantyzm”; Wschód i Zachód w literaturze modernizmu, mitologie, religie. Napisał doktorat o twórczości Tadeusza Micińskiego. Edytor jego polemicznego pisma Walka o Chrystusa (1911), wydanego po stu latach (Białystok 2011). Autor monografii: Heroiczna Apokalipsa. W kręgu idei i wyobraźni Tadeusza Micińskiego (Białystok 2012). Ostatnio wydał książkę: Słowacki i spadkobiercy. Studia i szkice (Białystok 2017).URSZULA M. PILCH – dr, adiunkt w Katedrze Historii Literatury Pozytywizmu i Młodej Polski na Wydziale Polonistyki Uniwersytetu Jagiellońskiego. Autorka książek: Język czterech żywiołów. Kreacje obrazów w liryce Juliusza Słowackiego (Kraków 2006) oraz Kto jestem? O podmiocie w poetyckim dwugłosie. Juliusz Słowacki i Tadeusz Miciński (Kraków 2010). Współredaktorka tomu: (wraz z A. Czabanowską-Wróbel) Młodopolski witalizm. Modernistyczne witalizmy (Kraków 2016). Wybrane nagrody i wyróżnienia: Indywidualna Nagroda Rektora Uniwersytetu Jagiellońskiego III stopnia, Nagroda im. Marty i Konrada Górskich (2011), dwukrotna Laureatka stypendium Ministra Edukacji Narodowej i Sportu, jak również laureatka stypendium z Funduszu im. Stanisława Estreichera.192

Training Study on Superconducting Coils of the LHC Sextupole Corrector Magnet

A study on a single sextupole coil, working under the same conditions as the full magnet, has been made to evaluate the effect of the azimuthal pre-compression and the longitudinal pre-tension on the training of superconducting coils. A testing device has been used that allows to test individual sextupole type coils in a cryostat at 4.2 K by exerting variable pre-stresses in situ. The paper describes the tests made with this device and discusses the results obtained for different pre-stress conditions and for different central island materials, in particular G-10 and stainless steel

Training Tests on Single Superconducting Coils of Sextupolar Correctors for LHC

The precompression of the coils is considered to be one of the most important parameters to achieve good training performance in a superconducting magnet. In order to better understand and optimise precompression, a test device has been created that allows to test individual coils in a cryostat at 4.2 K exerting a variable precompression in situ. The paper describes the design, construction and calibration of the testing device, the test instrumentation and the results of the first experiments with sextupolar coils. This work was realised in the framework of a collaboration between CERN and CEDEX/Spain