Test Results for RD3c, A Nb3Sn Common-Coil Racetrack Dipole Magnet
Test Results for RD3c, A Nb3Sn Common-Coil Racetrack Dipole Magnet
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2011-04
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通讯作者：
A. Lietzke
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作者：
A. Lietzke
3LA05 SC-MAG#771 LBNL-49916 RD3c（Nb 3 Sn 共线圈跑道偶极磁铁）的测试结果 A.F. Lietzke、S. Caspi、M. CoccoJi、D.R. Dietderich、P. Ferracin、S.A. Gourlay R.R. Hafalia、L. Chiesa、A.D. Mclnturff、G. Sabbi 和 R.M.本文报道了 Scanlan 具有扁平跑道线圈的良好场质量。摘要- 劳伦斯伯克利实验室的超导磁体小组一直在开发由脆性超导体制成的经济型高场加速器磁体的赛道技术。最近的测试表明：I) 坚固、可重复使用、双层、平坦跑道、缠绕和反应 Nb3Sn 线圈，2) 可重复使用、易于组装的线圈支撑结构，可最大限度地减少导体移动，以及 3) 第一偶极场，不会退化。 RD3c 是我们第一次尝试比较测量的和计算的场谐波。将单层 Nb3Sn 扁平跑道内线圈缠绕在孔板的两侧，然后进行反应并灌封（如前所述）。将硬垫片缠绕到内部线圈中，以调整几何场谐波，并识别硬垫片带来的任何问题。使用热旋转线圈进行谐波测量还需要相当厚的钻孔板（对于 35mm OD 抗低温恒温器）。内线圈模块夹在两个现有的外线圈模块之间，并在可重复使用的磁轭和壳体加载结构内施加预应力。讨论了磁铁的性能，并与计算结果进行了比较。二.测试准备 A. 目标和设计约束 RD3c 被认为是一种经济的线圈配置，它将评估我们纠正由低成本、高工程电流密度、扁平、共线圈跑道线圈产生的场误差的能力。经济且符合索引术语——磁铁、超导、Nb3Sn、跑道、测试结果、磁性测量。一、简介 普通线圈原理，施加了以下约束： I) RD3b 的外线圈、磁轭和壳体结构必须重复使用。 2) 谐波校正插入线圈需要是扁平跑道线圈，每层只有一个垫片。 3) 这些插入线圈必须制造为坚固的独立线圈模块，可以插入 RD3 的外部线圈模块之间。 4) 不会做出任何努力来纠正上下不对称四极杆，5) 孔板通道必须足够大以容纳 35mm 直径的旋转线圈探头。为了同时测试可靠性，插入线圈必须采用易于应用的最佳快速训练、可靠绝缘技术来构造。如果随后发现训练速度很慢，则可以使用粘滑运动诊断来定位滑动。劳伦斯伯克利国家实验室的 HE 超导磁体小组一直在为未来高能加速器开发高场超导 Nb、Sn 磁体技术。在电流密度、峰值场和降低成本方面取得了实质性进展。 D20 证明 Nb、Sn 导体可用于加速器品质 coS 偶极子 [I]。未来的加速器将需要更具成本效益的磁铁。这激发了对跑道共线圈磁体的探索[2-4]。一系列成功的测试证明了控制制造、组装和机械支撑的能力[4, 5]。最近的工作重点是评估跑道磁铁以更低的成本实现更高磁场的能力，同时保留 cosS 磁铁的可靠性和磁场质量。 RD3c 是全尺寸磁体系列中的最新测试，它用大孔径谐波校正模块取代了 RD3b 的小孔径高磁场插入模块。这项评估与实现手稿相关的困难的尝试的结果于 2002 年 8 月 6 日收到。这项工作得到了科学、高能与核物理办公室的支持。高能物理，美国能源部，合同 DE-AC03-76SF00098。 AJI 作者来自劳伦斯伯克利国家实验室，CA 94720 USA（5 10-486-4042 或 4572；传真：510-486-53 10；电子邮件：1 chiesa@lbl.gov、AFLietzke@lbl.gov）。 T B. 磁体参数 图 I 显示了由上述约束产生的磁体横截面。谐波校正模块插在 RD3b 的外线圈模块之间。与 RD3b 一样，插入模块使用铝青铜孔板来分隔两个单层线圈，该线圈具有内部斜坡以反转穿过孔板的电流方向，无需内部接头。与 RD3b 相比，每个线圈在前一个磁场最大值附近使用了一个大垫片，以抵消外部线圈产生的大正六极杆。每个线圈有 16 匝，分成两个相等的组。钻孔板足够厚（39.5 毫米），可以插入直径为 35 毫米的旋转线圈探头，同时足够坚硬，可以在穿过钻孔（靠近端部）的外部线圈块上施加预应力。图 I. RD3c 的磁体横截面：谐波校正、训练和磁测量测试。 RD3c 的性能限制与表 I 中的 RD3b 进行了比较。RD3c 的插入线圈使用与 RD3b 的插入线圈相同的电缆。由于处于较低磁场，这导致外部线圈将磁体的电流限制设置为 11.9KA。表J
3LA05 SC-MAG#771 LBNL-49916 Test Results for RD3c, a Nb 3 Sn Common-Coil Racetrack Dipole Magnet A.F. Lietzke, S. Caspi, M. CoccoJi, D.R. Dietderich, P. Ferracin, S.A. Gourlay R.R. Hafalia, L. Chiesa, A.D. Mclnturff, G. Sabbi and R.M. Scanlan good field-quality with flat racetrack coils is reported herein. Abstracl- The Superconducting Magnet Group at Lawrence Berkeley Laboratory has been developing racetrack technology for economical, high-field accelerator magnets from brittle superconductor. Recent tests have demonstrated I) robust, reusable, double-layer, flat racetrack, wind & react Nb3Sn coils, 2) a reusable, easily assembled, coil-support structure that can minimize conductor movement, and 3) 1ST dipole fields, with no degradation. RD3c is our first attempt to compare measured and calculated field harmonics. A single-layer, Nb3Sn , flat racetrack inner-coil was wound on both sides of a bore-plate, and then reacted and potted (as previously). Hard spacers were wound into the inner coils, to adjust the geometric field harmonics, and identify any problems from hard-spacers. Harmonic measurements with a warm rotating coil also required a considerably thicker bore-plate (for the 35mm OD anti-cryostat). The inner coiJ~module was sandwiched between two existing outer-coil modules, and pre-stressed within the reusable yoke & shell loading structure. The magnet's performance is discussed, and compared with calculations. II. TEST PREPARATION A. Goals and Design Constraints RD3c was conceived as an economical coil configuration that would assess our ability correct the field errors generated by low-cost, high engineering current-density, flat, common- coil racetrack coils. To be economical, and consistent with Index Terms-Magnets, Superconducting, Nb3Sn, Racetrack, Test Results, Magnetic Measurements. I. INTRODUCTION common-coil philosophy, the following constraints were imposed: I) RD3b's outer coils, yoke and shell structure must be re-used. 2) The harmonic-correction insert coils needed to be flat racetrack coils with only one spacer per layer. 3) These insert coils must be fabricated as a rugged independent coil- module that could be inserted between RD3's outer coil modules. 4) No effort would be made to correct the up-down asymmetric quadrupole, 5) Bore-plate access must be large enough to accept a 35mm diameter rotating-coil probe. To simultaneously test reliability, the insert coil must be constructed with the best rapid-training, reliable insulation technology that could be readily applied. If the training were subsequently discovered to be slow, stick-slip motion diagnostics would be available to localize the slippages. HE superconductiilg magnet group at the Lawrence Berkeley National Laboratory has been developing high- field, superconducting Nb, Sn magnet technology for future high-energy accelerators. Substantial progress has been made in current density, peak field and cost reduction. D20 demonstrated that Nb, Sn conductor could be used in an accelerator quality cosS dipole [I]. More cost-effective magnets will be needed for future accelerators. This motivated the exploration of racetrack common-coil magnets [2-4]. A series of successful tests demonstrated the ability to control fabrication, assembly and mechanical support [4 , 5]. Recent efforts have focused upon assessing Ihe ability of racetrack magnets to achieve higher fields, at less cost, while retaining the reliability and field-quality of cosS magnets. RD3c, the most recent test in the full-size magnet series, replaced RD3b 's small-bore, high-field insert module with a large-bore, hannonic-correction module. The results of this attempt to assess the difficulties associated with achieving Manuscript received August 6, 2002. This work was supported by Office of Science, High Energy & Nuclear Physics, Div. High Energy Phys ics, U.S. DOE, Contract DE-AC03-76SF00098 . AJI the authors are with Lawrence Berkeley National Laboratory, CA 94720 USA (5 10-486-4042 or 4572; fax : 510-486-53 10; e-mail: 1 chiesa@lbl.gov, AFLietzke@lbl.gov). T B. Magnet Parameters Figure I shows the magnet cross-section that resulted from the above constraints. The harmonic-correction module was inserted between RD3b 's outer coil modules. Like RD3b, the insert module used an aluminum-bronze bore-plate to separate two single layer coils that had an internal ramp to reverse the current direction across the bore-plate, without an internal splice. In contrast to RD3b, each coil used a large spacer near the previous field maximum, to counteract the large positive sextupole generated by the outer coils. Each coil had 16 turns in two equal blocks. The bore-plate was thick enough (39.5 mm) to allow access for a 35mm diameter rotating coil probe, while stiff enough to pre-stress the outer coil-block where it crossed the bore hole (nears the ends). Fig. I. The magnet cross-section for the RD3c: a harmonic correction, training, and magnetic measurement test. RD3c's performance limits are compared with RD3b in Table I. RD3c' s insert coil used the same cable as RD3b 's insert. Being at a lower field, this caused the outer coils to set the magnet's current limitation at 11.9KA. TABLE J