Design and construction of a 1 m model of the low current superconducting quadrupole for the LHC insertions

About one hundred individually powered low current superconducting quadrupoles will be installed in the LHC insertions. One of the design requirements was to keep the excitation current of the magnet below 6 kA in view of minimizing the costs of the powering circuits. The design of the quadrupole is based on a 8.2 mm NbTi cable, and is designed for a nominal gradient of 200 T/m at 1.9 K. In this paper we present the design of the quadrupole and discuss the construction details of the 1 m single aperture model which has been recently completed

Launching of Series Fabrication of the LHC Main Quadrupoles

A collaboration agreement between CERN and CEA-Saclay resulted in the successful development and construction of prototypes of the LHC main superconducting quadrupole magnets and their assembly into cold masses. A call for tender was issued in October 1999 and led to the adjudication of a contract to ACCEL Instruments. A number of components will be provided by CERN to be used either directly by ACCEL for integration into the cold mass units or by sub-suppliers before delivery to ACCEL. During the series fabrication CEA's engineers and technicians, already experienced from their prototype work, will ensure the technology transfer and the technical follow up in the factory. ACCEL had to adapt two large fabrication halls to the needs of the magnet fabrication and the cold mass assembly. Procedures for a tight quality assurance and the logistics for the timely supply of components and a high production rate are being established in close collaboration by the three parties concerned

Development of Superconducting Tuning Quadrupole Corrector (MQT) Prototypes for the LHC

The main quadrupoles of the Large Hadron Collider (LHC) are connected in families of focusing and defocusing magnets. In order to make tuning corrections in the machine a number of quadrupole corrector magnets (designated MQT) are necessary. These 56 mm diameter aperture magnets have to be compact, with a maximum length of 395 mm and a coil radial thickness of 5 to 7.5 mm, while generating a minimum field gradient of 110 T/m. Two design options have been explored, both using the "counter-winding" system developed at CERN for the fabrication of low cost corrector coils. The first design, with the poles composed of two double-pancake coils, each counter-wound using a single wire, superposed to create 4-layer coils, was developed and built by ACCEL Instruments GmbH. A second design where single coils were counter-wound using a 3-wire ribbon to obtain 6-layer coils was developed at CERN. This paper describes the two designs and reports on the performance of the prototypes during testing

Performance of the single and twin-aperture models of the 6 kA superconducting quadrupole for the LHC insertions

The LHC dispersion suppressors and matching sections will be equipped with individually powered superconducting quadrupoles with an aperture of 56 mm. In order to optimise the parameters and cost of the magnets and of their powering, the quadrupole has been designed on the basis of an 8.2 mm wide Rutherford-type cable for a nominal current of 5300 A, corresponding to a gradient of 200 T/m at 1.9 K. In order to validate the design two 1-m single-aperture quadrupoles and one twin-aperture quadrupole have been built and tested. In this report we describe the construction features of the magnets and present the results of the magnet tests. (4 refs)

Performance of the LHC Arc Superconducting Quadrupoles Towards the End of their Series Fabrication

The fabrication of the 408 main arc quadrupole magnets and their cold masses will come to an end in summer 2006. A rich collection of measurement and test data has been accumulated and their analysis is presented in this paper. These data cover the fabrication and the efficiency in the use of the main components, the geometrical measurements and the achieved dimensional precision, the warm magnetic measurements in the factory and the performance at cold conditions, especially the training behaviour. The scrap rate of the Nb-Ti/Cu conductor as well as that of other components turned out to be acceptably low and the quench performance measured was in general very good. Most quadrupoles measured so far exceeded the operating field gradient with one or no quench. The multipole content at cold was measured for a limited number of quadrupoles in order to verify the warm-to-cold correlation. From the point of view of field quality, all quadrupoles could be accepted for the machine. The measures taken to overcome the problem of a too high permeability of a batch of collars are discussed

Double blind, randomized, placebo controlled clinical trial for the treatment of diabetic foot ulcers, using a nitric oxide releasing patch: PATHON

<p>Abstract</p> <p>Background</p> <p>Diabetes Mellitus constitutes one of the most important public health problems due to its high prevalence and enormous social and economic consequences. Diabetic foot ulcers are one of the chronic complications of diabetes mellitus and constitute the most important cause of non-traumatic amputation of inferior limbs. It is estimated that 15% of the diabetic population will develop an ulcer sometime in their lives. Although novel therapies have been proposed, there is no effective treatment for this pathology. Naturally produced nitric oxide participates in the wound healing process by stimulating the synthesis of collagen, triggering the release of chemotactic cytokines, increasing blood vessels permeability, promoting angiogenic activity, stimulating the release of epidermical growth factors, and by interfering with the bacterial mitochondrial respiratory chain. Topically administered nitric oxide has demonstrated to be effective and safe for the treatment of chronic ulcers secondary to cutaneous leishmaniasis. However, due to their unstable nitric oxide release, the topical donors needed to be applied frequently, diminishing the adherence to the treatment. This difficulty has led to the development of a multilayer polymeric transdermal patch produced by electrospinning technique that guarantees a constant nitric oxide release. The main objective of this study is to evaluate the effectiveness and safety of this novel nitric oxide releasing wound dressing for the treatment of diabetic foot ulcers.</p> <p>Methods and design</p> <p>A double-blind, placebo-controlled clinical trial, including 100 diabetic patients was designed. At the time of enrollment, a complete medical evaluation and laboratory tests will be performed, and those patients who meet the inclusion criteria randomly assigned to one of two groups. Over the course of 90 days group 1 will receive active patches and group 2 placebo patches. The patients will be seen by the research group at least every two weeks until the healing of the ulcer or the end of the treatment. During each visit the healing process of the ulcer, the patient's health status and the presence of adverse events will be assessed. Should the effectiveness of the patches be demonstrated an alternative treatment would then be available to patients.</p> <p>Trial registration</p> <p>NCT00428727.</p

Results of 3-dimensional structural FE-modeling of the coil end-regions of the LHC main dipoles

The transition region between the straight part and the ends of the coils of the LHC model and prototype dipole magnets are often identified as the origin of training quenches. In order to study how the discontinuities in the material properties of these regions affect coil pre-stress and possibly gain more insight in the quench behavior, a program was set up at CERN to analyze by 3D-FEM these particular regions. The ACCEL team, who performed a similar analysis for the main quadrupoles of the Superconducting Supercollider SSC, is entrusted with this program. In this paper we report on the results of 3D-modeling and analysis of the coil return end region, including the complete coil mass, of a 1-m single bore model magnet. This magnet represents all relevant features of the "two-in-one" LHC main dipole design concerning the winding configuration, the collar pack, the yoke, and the outer shell representing the He-vessel. The transition region between coil ends and straight section is modeled by slicing the magnet down to individual collar laminations per elementary level. The two-layer winding pack is represented with all individual conductor blocks, wedges, end spacers, and the interlayer spacer. Results will be presented for load cases with pre-stress after assembly at room temperature, after cool-down, and under operation at maximum current. Critical stress locations were identified in the transition into the pole free section of the magnet and in the bent part. Shimming of the coils, as well as impact from material choices and suitable alternatives are discussed. (3 refs)

Quench testing of HTS sub-elements for 13 kA and 600 A leads designed to the specifications for the CERN Large Hadron Collider project

Ability to safely withstand and survive self quench conditions is an important consideration in the design and utilisation of HTS current leads. The provision of a non superconducting shunt path allows current to be diverted in the event of a transition to the normal state. This shunt should allow very rapid transfer of current out of the HTS material and be able to safely support the full load current for the time required to detect the fault and reduce the current to zero. However, the shunt should also be designed to minimise the increased heat load which will result from it's addition to the lead. Test of leads based on melt cast BSCCO 2212 utilising a fully integrated silver gold alloy sheath are described. The HTS sub- elements form part of a full 13 kA lead, designed to the specifications of CERN for the LHC project. The sub-elements proved able to fully comply with and exceed the quench performance required by CERN. The HTS module was quenched at the full design current and continued to maintain this current for a further minute in the absence of any coolant without any damage being incurred or degradation of subsequent performance. Results were in full agreement with calculated quench performance. Work continues on similar modules for a 600 A lead. (5 refs)

New cryogen-free design for superconducting mini-gap undulators

10.1109/TASC.2005.849539IEEE Transactions on Applied Superconductivity152 PART II1232-1235ITAS