EUCARD magnet development

The FP7-EuCARD work package 7 (WP7), "HFM: Superconducting High Field Magnets for higher luminosities and energies" is a collaboration between 12 European institutes and firms with the objective of developing high field magnet technology. WP7 foresees to construct a 13 T dipole with a 100 mm aperture, a B = 6 T high temperature superconductor (HTS) dipole insert, a superconducting HTS link and a superconducting helical undulator.Comment: 5 pages, contribution to the EuCARD-AccNet-EuroLumi Workshop: The High-Energy Large Hadron Collider, Malta, 14 -- 16 Oct 2010; CERN Yellow Report CERN-2011-003, pp. 45-4

Warm Magnets

Warm magnets are magnets that function in normal ambient temperature conditions. These types are mostly using a soft steel yoke for field amplification and either Copper or Aluminium coils or permanent magnets to generate the field. Magnets powered with such normal-conducting coils are often also called classical, iron dominated or resistive magnets. Since decades these types of magnets are the workhorse for most linear and circular accelerators and beam transfer lines.Comment: 20 pages, contribution to the CAS - CERN Accelerator School: Introduction to Accelerator Physic

Superconducting Magnets

Superconductivity allows to construct and operate magnets at field values beyond 2 Tesla, the practical limitation of normal-conducting magnets exploiting ferro-magnetism. The field of superconducting magnets is dominated by the field generated in the coil. The stored energy and the electromagnetic forces generated by the coil are the main challenges to be overcome in the design of these magnets. For further reading you may consult the following books: [1], [2], [3], [4] or the proceedings of two specialized CAS courses: [5] and [6].Comment: 24 pages, contribution to the CAS - CERN Accelerator School: Introduction to Accelerator Physic

Prospective, blind study of the triple stimulation technique in the diagnosis of ALS

Abstract Objective: To evaluate the diagnostic yield of magnetic cortical stimulation with the triple stimulation technique (TST) to identify upper motor neuron (UMN) involvement in patients suspected of having ALS. Methods: Fifty-nine patients were recruited to undergo TST in addition to the standard work-up for suspected motor neuron disease. TST combines transcranial magnetic stimulation of the motor cortex with collision studies, which results in a higher sensitivity in detecting UMN involvement. Primary outcome was the number of abnormal TST results in patients with possible ALS. The positivity rate was converted to the number needed to test with TST (NN-TST) for one extra diagnosis of ALS. Results: Fifty patients underwent TST. In the total group (n 059), 18 patients had a motor neuron disorder but did not fulfil criteria for 'probable' or 'definite' ALS. In four of these patients TST was abnormal (NN-TST, 4.5). One TST was erroneously interpreted as abnormal. TST findings were normal in inclusion body myositis and peripheral nerve disorders. Conclusion: This prospective and blind study confirms open studies of TST in the evaluation of ALS. We suggest that TST can be used to arrive at a diagnosis of 'probable' or 'definite' ALS in patients lacking UMN signs in the upper extremities

Analysis of variance for testing method of cement in determination of strength

AbstractThe statistical tools such as descriptive statistics, full factorial design and analysis of source of variation were used to identify the potential factors that impact the validity of testing method for determining the strength of cement. The results showed that personal error impacted both accuracy and precision of test greatly. Experimental time associated with temperature fluctuation resulted in strength variation but did not impact the precision of test in all curing ages. Different compactions did not impact the precision of test but resulted in the strength variation on 3 d and 28 d significantly. Different methods for the initial moist air curing significantly impacted the precision of testing method and resulted in the strength variation of cement on 1 d

High-temperature superconducting screens for magnetic field-error cancellation in accelerator magnets

Accelerators magnets must have minimal magnetic field imperfections to reduce particle-beam instabilities. In the case of coils made of high-temperature superconducting (HTS) tapes, the magnetization due to persistent currents adds an undesired field contribution, potentially degrading the magnetic field quality. In this paper we study the use of superconducting screens based on HTS tapes for reducing the magnetic field imperfections in accelerator magnets. The screens exploit the magnetization by persistent currents to cancel out the magnetic field error. The screens are aligned with the main field component, such that only the undesired field components are compensated. The screens are self-regulating, and do not require any externally applied source of energy. Measurements in liquid nitrogen at 77 K show for dipole-field configurations a significant reduction of the magnetic field error up to a factor of four. The residual error is explained via numerical simulations accounting for the geometric defects in the HTS screens, achieving satisfactory agreement with experimental results. Simulations show that if screens are increased in width and thickness, and operated at 4.5 K, field errors may be eliminated almost entirely for the typical excitation cycles of accelerator magnets

The high field magnet program in Europe

With the LHC, magnets of 10 T peak flux density Nb-Ti technology were developed and this technology reached full maturity. The next step in flux density level, with a peak in the range of 15 T, will be needed for the LHC Phase II upgrade. For this upgrade the temperature margin and radiation resistance of the Nb-Ti coil technology is not sufficient. Beginning 2008 CERN started a program to develop high field magnets for LHC upgrades and other future programs. For this mostly Nb$_{3}$Sn conductors will be employed, but also HTS conductors will be considered. In this paper an overview will be presented of the projects for which this HFM technology will be needed. The program will be presented in terms of R&D chapters and work packages. The need and opportunities for collaborations with other institutes will be discussed