Conceptual design of 20 T dipoles for high-energy LHC

Availability of 20 T operational field dipole magnets would open the way for a 16.5 TeV beam energy accelerator in the LHC tunnel. Here we discuss the main issues related to the magnet design of this extremely challenging dipole: main constraints, superconductor choice, coil lay-out, iron, forces and stresses, and field quality. A tentative cost estimate is also given. The present technology, based on Nb-Ti and now near to be extended to Nb3Sn superconductor, would allow reaching 15 T operational field. To reach 20 T, HTS conductors capable to carry 400 A/mm2 at 15-20 T under transverse stress of 150-200 MPa are an essential element.Comment: 7 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. 13-1

Electromagnetic Design of Superconducting Quadrupoles

We study how the critical gradient depends on the coil lay-out in a superconducting quadrupole for particle accelerators. We show that the results relative to a simple sector coil are well representative of the coil lay-outs that have been used to build several quadrupoles in the past 30 years. Using a semi-analytical approach we derive a formula that gives that critical gradient as a function of the coil cross-sectional area, of the magnet aperture, and of the superconducting cable parameters. This formula is used to evaluate the efficiency of several types of coil lay-outs (shell, racetrack, block, open mid-plane)

A Solution for Phase-one Upgrade of the LHC Low-beta Quadrupoles Based on Nb-Ti

We discuss the possibilities of upgrading the LHC triplet quadrupoles by significantly increasing their aperture (and length), using the Nb-Ti cable of the main dipoles. The goal of this first phase in upgrading the triplet is to allow a rapid improvement of the luminosity mostly by removing limitations related to the triplet aperture. Neither the experimental area, including the TAS, nor the basic optics are modified. By the same token, steps are made to allow a moderate increase of the luminosity within the capabilities of the existing detectors. The triplet aperture is sized to decrease the collimator impedance below significance, allow a potential increase of the luminosity by some 50% or up to a factor of 2 with an external ancillary system acting on the geometrical loss factor. Some extra aperture is foreseen to lower the power deposition, to improve field quality and/or to allow a stronger focusing in the event some baseline beam parameters would not be reached. In this way, the proposed phase-one upgrade is versatile and should allow improved performance in a large range of situations

An Estimate of Multipolar Errors in the LHC Dipoles

Magnetic measurements of 60 collared coils and of 14 cryomagnets are available for the LHC dipoles. These data are used to work out an estimate of the systematic and random components of the field harmonics, in the hypothesis of a complete mixing of the manufacturers

Impact of the First Powering Cycles on the LHC Superconducting Dipole Coil Geometry

The impact of the first powering cycles on the LHC superconducting dipoles coil geometry has been investigated. Dedicated magnetic measurements have been performed to estimate the changes in the geometric component of the harmonics, caused by the last highest Lorentz force the coil has ever experienced. Several magnets have been powered at increasing current steps while the field quality has been measured to quantify the changes in geometry. The effect of the thermal cycles has been also considered as well as the systematic differences between measurements before and after the quench training. The reconstruction of the coil geometry variations is discussed in terms of continuous modes of deformation as well as single block displacements

An estimate of the maximum gradients in superconducting quadrupoles

In this paper we show that the electromagnetic design of several superconducting quadrupoles, built for particle accelerators, can be rather well approximated by a 36 degree sector coil with a wedge, canceling the first two field harmonics. We therefore carry out a complete analysis of this lay-out, obtaining an approximated equation for the critical gradient as a function of the coil area, magnet aperture, and of the superconducting properties of the cable. Using this model, we estimate through numerical methods the maximum critical gradient that can be obtained in quadrupole of a given aperture for Nb-Ti, Nb-Ti-Ta and Nb3Sn

The Analyses on Bush Doctrine——In Addition to Expound the Historical Similarities among Bush Doctrine，

内容摘要 论文主要是对美国“布什主义”进行综合分析，通过布什主义与杜鲁门主义、尼克松主义的历史比较，寻绎其产生的历史和现实根源，阐述“布什主义”对国际社会带来的影响及未来走向。 第一章从国内和国际两方面对布什主义的研究现状进行梳理。作者认为布什主义是美国在冷战后的新形势下对外交政策调整的一个产物。其核心开始是反对恐怖主义对美国的袭击，以保护美国本土绝对安全为主要内容，后来逐渐成为一种国家安全战略，其核心是以反恐为借口，将势力拓伸到对美国具有威胁的世界任何地区及填补冷战后的战略真空，以确保美国的超级地位。 第二章从国内和国际两方面分析布什主义产生的原因。美国强大的国力、根深蒂固的种族优...Abstract The thesis analyzes mainly the origins of Bush Doctrine, its impacts on international society， and its tendency. The author compares Bush Doctrine with Truman Doctrine and Nixon Doctrine, in order to find the historical traits of Bush Doctrine. The first part reviews the present studies on Bush Doctrine. It believes that Bush Doctrine is the result of American foreign policy adjustme...学位：历史学硕士院系专业：人文学院历史学系_世界史学号：20010201

Pharmacological manipulation of L-carnitine transport into L6 cells with stable overexpression of human OCTN2

Abstract.: The high-affinity Na+-dependent carnitine transporter OCTN2 (SLC22A5) has a high renal expression and reabsorbs most filtered carnitine. To gain more insight into substrate specificity of OCTN2, we overexpressed hOCTN2 in L6 cells and characterized the structural requirements of substances acting as human OCTN2 (hOCTN2) inhibitors. A 1905-bp fragment containing the hOCTN2 complete coding sequence was introduced into the pWpiresGFP vector, and L6 cells were stably transduced using a lentiviral system. The transduced L6 cells revealed increased expression of hOCTN2 on the mRNA, protein and functional levels. Structural requirements for hOCTN2 inhibition were predicted in silico and investigated in vitro. Essential structural requirements for OCTN2 inhibition include a constantly positively charged nitrogen atom and a carboxyl, nitrile or ester group connected by a 2-4-atom linker. Our cell system is suitable for studying in vitro interactions with OCTN2, which can subsequently be investigated in viv