本文選題：低溫永磁波蕩器　切入點：磁體冷卻技術(shù)　出處：《中國科學(xué)院研究生院(上海應(yīng)用物理研究所)》2017年博士論文　論文類型：學(xué)位論文

【摘要】：低溫永磁波蕩器(Cryogenic Permanent Magnet Undulator,簡稱CPMU)利用稀土永磁材料釹鐵硼或鐠鐵棚在低溫下的剩磁及內(nèi)稟矯頑力大幅增大的特性,通過使磁體工作在50K~150K的低溫環(huán)境,獲得相比于常規(guī)真空內(nèi)波蕩器(In-vacuum Undulator,簡稱IVU)高約30%~50%的磁場性能。低溫永磁波蕩器是近幾年同步輻射光源插入件技術(shù)發(fā)展方向的一大熱點,它依賴高性能永磁鐵在低溫下的特殊性能大幅提高了波蕩器的峰值磁場,因而對光源束流品質(zhì)的提高有著重要的作用。當(dāng)前,CPMU仍處于試制階段,低溫冷卻是其研制的關(guān)鍵技術(shù)之一。本論文對CPMU及其冷卻技術(shù)的國內(nèi)外研究工作進行了較全面的調(diào)研,對低溫永磁波蕩器冷卻的總體方案、熱負載特性、磁體冷卻回路和傳熱特性、冷卻結(jié)構(gòu)和調(diào)溫方案,磁體冷縮變形等開展了細致且深入的理論分析和實驗研究工作,驗證了仿真模型和分析結(jié)果的可靠性和適用性。具體研究內(nèi)容如下:1)CPMU磁體冷卻的總體方案設(shè)計。根據(jù)CPMU樣機的物理和冷卻設(shè)計要求,結(jié)合所采用的釹鐵硼磁化塊的磁物性特點以及磁結(jié)構(gòu)特點,分析CPMU研制過程(如先磁場測試與墊補再上線運行)各階段的低溫測試及運行的特點和要求,確定上海光源的釹鐵硼CPMU樣機采用過冷液氮冷卻方式并采用導(dǎo)冷隔熱組件結(jié)構(gòu)對CPMU的內(nèi)大梁及其上固定的磁體進行傳導(dǎo)冷卻的總體方案。2)CPMU熱負載研究。首先對CPMU在線運行和離線磁測兩種工況下對磁體冷卻的要求進行分析,對各工況下的熱負載來源進行綜合分析,對熱負載的各組成部分的關(guān)鍵影響因素構(gòu)建理論模型進行研究,合理確定其設(shè)計工況。其次,利用理論分析模型對CPMU試驗件進行熱負載的分析,以減小漏熱量為目標,對相關(guān)結(jié)構(gòu)進行優(yōu)化設(shè)計;然后,對其進行實驗測試,修正相關(guān)理論分析模型,探索熱負載的實驗測量方法,實驗論證了采用導(dǎo)冷組件傳熱法進行熱負載分析相比于液氮換熱法的合理和準確性。最后,根據(jù)經(jīng)驗證并改進了的CPMU熱負載理論分析方法和實驗測試方法,對CPMU樣機進行了靜態(tài)熱負載的理論分析和離線磁測工況下的實驗測試。CPMU樣機的離線測試的工作溫區(qū)120K~170K,冷量消耗為200W~418W,滿足離線磁場測試的溫區(qū)調(diào)節(jié)要求。此外,CPMU樣機成功安裝與上海光源在線測試,測到了220W的最大動態(tài)熱負載,基本符合動態(tài)熱負載估算值200W。3)CPMU磁體的冷卻回路研究。首先對CPMU磁體冷卻回路的布局方案進行定性分析,利用有限元分析方法對不同方案進行模擬分析,結(jié)合CPMU磁體溫度均勻性的要求以及過冷液氮的流動阻力和液氮均等分配問題,對CPMU上下大梁采用兩條并聯(lián)冷卻回路分別進行冷卻的方案。其次,對CPMU磁體冷卻回路建立了對流換熱理論分析模型,從過冷液氮的流態(tài)、流動阻力、冷卻工質(zhì)過冷度等方面進行優(yōu)化,確定了冷卻管內(nèi)徑為8mm。再次,結(jié)合CPMU熱負載分析結(jié)果,對冷卻回路中過冷液氮的流動換熱參數(shù)進行分析,研究其流動阻力、對流換熱系數(shù)、對流換熱熱阻等參數(shù)的變化規(guī)律,分析得出CPMU磁體冷卻結(jié)構(gòu)中對流換熱熱阻僅占總熱阻的1.3%,可以被忽略。最后,利用CPMU試驗件對CPMU磁體的冷卻回路進行了試驗研究,實驗證明CPMU試驗件所采用的冷卻回路布局方案具有大梁溫度均勻性受冷卻回路過冷液氮進出口溫差影響小的優(yōu)點,該方案已應(yīng)用于CPMU樣機的研制中。4)CPMU磁體冷卻結(jié)構(gòu)和調(diào)溫方案研究。首先,結(jié)合CPMU的熱負載理論分析結(jié)果與熱源分布特點,提出了對CPMU樣機磁體及其內(nèi)大梁的端部和吊桿附近采用不同的導(dǎo)冷隔熱組件的冷卻結(jié)構(gòu)方案。之后,以降低CPMU磁體內(nèi)大梁溫度不均勻性為目標,利用有限元分析軟件對導(dǎo)冷隔熱組件的設(shè)計方案建立仿真模型并進行了優(yōu)化和模擬驗證。最后,對CPMU樣機變工況過程中的溫度分布變化與熱負載變化進行了試驗研究。CPMU樣機在離線磁測過程中大梁最大溫差始終低于2K,為CPMU樣機磁場相位誤差達到設(shè)計要求提供了有力保證。5)CPMU磁體冷縮變形的研究。首先,建立了CPMU磁體冷縮變形的理論分析數(shù)值模擬仿真模型。然后,利用CPMU磁測平臺上集成的磁間隙測量裝置對CPMU低溫下的磁間隙進行測量實驗,驗證了磁間隙冷縮變形的仿真模型和分析結(jié)果的準確性。此外,針對CPMU樣機磁場相位誤差隨溫度發(fā)生變化的現(xiàn)象,利用有限元分析軟件對CPMU樣機低溫下的冷縮變形分布進行仿真模擬研究,分析CPMU磁間隙冷縮變形對峰值磁場分布的影響。結(jié)合CPMU樣機的低溫磁測結(jié)果,得出了CPMU磁體內(nèi)大梁冷縮變形引起的磁間隙變化一致性是CPMU低溫下磁場相位誤差的關(guān)鍵影響因素之一,指出了CPMU樣機的改進方向。通過對CPMU樣機局部磁場進行室溫下的預(yù)墊補,補償磁間隙低溫下的不一致冷縮變形,使CPMU樣機的相位誤差在室溫與低溫下均小于3度,達到國際水平。
[Abstract]:Low temperature permanent magnet undulator (Cryogenic Permanent Magnet Undulator, referred to as CPMU) based on the characteristics of rare earth permanent magnet materials or praseodymium neodymium iron boron iron shed at low temperature, remanence and intrinsic coercivity increases sharply, the magnet in the low temperature environment of 50K~150K, was compared with the conventional vacuum undulator (In-vacuum Undulator referred to as IVU) high performance magnetic field of about 30%~50%. Low temperature permanent magnet undulator is a hot topic in recent years, the synchrotron radiation source insert technology development direction, it depends on the high performance permanent magnet properties at low temperature, a substantial increase in the peak magnetic undulator, plays an important role in the quality of light beam flow improved. At present, CPMU is still in the trial stage, low temperature cooling is one of the key technologies to develop a more comprehensive research. This paper on the CPMU and its cooling technology at home and abroad research work on low temperature permanent magnet The overall scheme of undulator cooling, heat load, cooling circuit and heat transfer characteristics of magnet, cooling structure and temperature shrinkage deformation magnet program, carried out theoretical analysis and experimental research work detailed and thorough, verify the reliability of the simulation model and analysis results and applicability. The specific contents are as follows: 1) the overall design scheme of CPMU magnet cooling. According to the requirement of the CPMU prototype and physical cooling design, combined with the magnetic properties of NdFeB magnetic blocks and magnetic structure characteristics, analysis of the CPMU development process (such as the first field test and re shimming on-line operation characteristics and requirements of low temperature test) and the operation of each stage, Shanghai the source of Nd-Fe-B CPMU prototype using supercooled liquid nitrogen cooling and the overall scheme used in beam guide cold insulation structure of CPMU and the fixed magnet.2 CPMU heat conduction cooling) Study on load. The requirements of the magnet cooling CPMU online and offline magnetic operation under two conditions were analyzed under the condition of the heat load on the source of comprehensive analysis, the key factors of each part of the construction of the theoretical model of thermal load were studied, to determine a reasonable design conditions. Secondly, analyze the heat the load on the CPMU test by using the model of theory analysis, by Jian Xiaolou heat as the goal, to optimize the design of the relevant structure; then, the experimental test is carried out for the analysis, model updating theory, explore the experimental method to measure the thermal load. The experiment demonstrated that using conductance method heat transfer component thermal load analysis compared to the liquid nitrogen heat exchanger the method is reasonable and accurate. Finally, according to the CPMU verified and improved the thermal load of theoretical analysis and experimental method, the CPMU prototype of the static heat load theory The off-line test test.CPMU prototype analysis and off-line magnetic conditions of the working temperature range of 120K~170K, the consumption of cooling capacity is 200W~418W, meet the temperature regulation requirements off-line magnetic field test. In addition, the CPMU prototype successfully installed with Shanghai light source online testing, measuring up to 220W maximum dynamic thermal load, accord with dynamic thermal load estimated 200W.3) cooling circuit of CPMU magnet. The qualitative analysis of the first CPMU magnet cooling circuit layout scheme, simulation analysis of different schemes by using the finite element analysis method, combined with the requirements of CPMU magnet temperature uniformity and subcooled liquid nitrogen flow and distribution of liquid nitrogen. All the problems on the CPMU under the beam by two a parallel cooling circuit for respectively cooling scheme. Secondly, the CPMU magnet cooling circuit has established the theory of convection heat transfer analysis model, the flow state of the subcooled liquid nitrogen, flow resistance, Cooling subcooling degree has been optimized, the cooling pipe diameter is 8mm. again, with CPMU thermal load analysis, thermal parameters of the supercooled liquid nitrogen cooling circuit of the flow analysis on the flow resistance, heat transfer coefficient, convective heat transfer and thermal resistance variation parameters, analysis the CPMU magnet cooling structure in convective thermal resistance accounted for only 1.3% of the total thermal resistance, can be ignored. Finally, experiments were carried out using CPMU CPMU magnet cooling circuit of test pieces, and prove that the CPMU test of the cooling circuit layout case with beam temperature uniformity by the import and export of subcooled liquid nitrogen cooling circuit the advantages of small temperature difference, the development scheme has been applied in the prototype of CPMU.4 CPMU) study cooling structure and temperature regulation scheme with CPMU magnets. Firstly, the thermal load of the results of theoretical analysis and heat distribution characteristics, put forward Cooling structure of CPMU prototype magnet and its inner girder end and the boom near the cold conducting different insulation components. After that, in order to reduce the uneven temperature of CPMU magnet beam as target, using finite element analysis software design scheme to guide cold insulation of the simulation model is established and optimized and simulated. Finally, the prototype of CPMU variable temperature distribution and thermal conditions in the process of load change test has been carried out on the.CPMU prototype in the process of off-line magnetic beam maximum temperature is lower than 2K, the CPMU prototype field phase error to meet the design requirements to provide a strong guarantee and.5) CPMU magnet deformation research. Firstly, established the CPMU magnet and contraction the deformation of the theoretical analysis numerical simulation model. Then, the CPMU magnetic platform integrated magnetic gap measuring device using magnetic gap of CPMU low temperature measurement experiment, To verify the accuracy of the magnetic gap and simulation model and analysis results of deformation. In addition, the prototype of CPMU magnetic phase error changes with temperature and contraction of the phenomenon, the prototype of CPMU low temperature deformation simulation of distribution using finite element analysis software, CPMU analysis of the magnetic gap and contraction deformation effect on peak magnetic field combined with low temperature. The magnetic CPMU prototype, the CPMU magnet in the magnetic gap and beam deformation caused by the change of consistency is one of the key factors influencing the magnetic phase error CPMU under low temperature, pointed out the improvement direction of CPMU prototype. Through pre shimming at room temperature on CPMU prototype of the local magnetic field, the magnetic gap compensation under low temperature and inconsistent the phase error of deformation, the prototype of CPMU at room temperature and low temperature are less than 3 degrees, reached the international level.

【學(xué)位授予單位】：中國科學(xué)院研究生院(上海應(yīng)用物理研究所)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：TL503

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