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冲击波速度是状态方程试验中重要的测量数据,可用特殊靶来实现直接测量。根据实验室的条件,尝试自制台阶靶,通过条纹相机对台阶边缘两侧的光信号进行记录,可直观测算出靶内冲击波的瞬时平均速度。 相似文献
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惯性约束聚变冷冻靶系统中,为成功实现靶丸点火,冰层厚度均匀性需达到99%,表面粗糙度的均方根要小于1 μm。控制靶丸表面最大温差小于0.1 mK能满足以上点火要求。为研究辐射对惯性约束聚变间接驱动靶丸的温度场影响,建立了三维对称球腔冷冻靶系统的计算模型。考虑球腔内部激光入射口封口膜吸收率以及外部辐射温度对球腔内部温度场分布的影响,利用FLUENT软件对球腔冷冻靶温度场进行了数值模拟计算。研究表明:球腔由于自身具有的球对称几何结构,其内部的温度场分布更加均匀;受外界辐射影响,有窗侧靶丸表面温度较无窗侧温度高;辐射温度越高,靶丸表面的绝对温度越高,虽然靶丸表面的温差变化基本可忽略,但要防止由于外界辐射温度过高而导致的DT冰层均匀性恶化,应选用多层屏蔽罩结构降低辐射的影响;激光入射口封口膜吸收率大于0.2时,靶丸表面温差显著增大。 相似文献
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通过建立三维柱腔冷冻靶计算模型,研究了外界环境辐射对间接驱动冷冻靶靶丸及燃料冰层温度场的影响。考虑柱腔内部激光入射孔(LEH)膜透光率对柱腔内靶丸和冰层温度场分布的影响,利用COMSOL软件对柱腔冷冻靶温度场进行了数值模拟计算。研究结果表明:受外界辐射影响,靶丸表面温度场呈两极热、赤道冷分布;LEH膜透光率越大,靶丸外表面温差和冰层内表面温差越大。当LEH膜透光率小于1%时,冰层内表面最大温差低于0.1 mK,可满足冰层均化和保持的要求。实验中,通过在LEH膜上镀不同厚度的铝层调控其透光率,并选择LEH膜镀铝层厚度为35 nm的冷冻靶开展了氘氘冷冻均化实验。结果表明:当LEH膜上的镀铝层厚度为35 nm时,冰层的保持能力得到大幅提升。从X射线相衬图像可知,冰层的厚度均匀性约为80.2%,粗糙度约为1.65 μm,平均厚度约为50.5 μm。 相似文献
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为在冷冻靶上成功实现惯性约束核聚变点火,需在打靶前将冷冻靶丸内冰层温度降低1.5 K。针对冷冻靶快速降温过程温度场发生突变导致冰层质量恶化的问题,数值研究了快速降温过程中冷冻靶温度场的瞬态特性,并提出了优化降温方案。数值模拟基于Boussinesq假设,通过UDF编程,获得了降温速率的影响规律,并分析比较了不同延迟时间下延迟降温的数值结果。结果表明:降温开始时,最大温差急剧增大但最终趋于稳定;减小降温速率,可有效改善靶丸表面温度的均匀性,延长冰层的生存时间,使降温结束时冰层质量满足要求;具有特定延迟时间的延迟降温能改善靶丸外表面温度的均匀性从而增加冰层的生存时间,且存在最佳延迟时间使冰层的生存时间最长。 相似文献
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在惯性约束核聚变冰层均化实验阶段,观测到充气管内冰晶无法保持,从而不能堵管,靶丸直接与高温氘气源连接,无法继续实验。为解决难以堵管的问题,本文建立了三维冷冻靶系统计算模型,研究了辐射条件下屏蔽罩温度、封口膜透射率及铝套筒表面发射率等因素对冷冻靶靶丸表面及充气管沿程温度特性的影响规律。结果表明:改变封口膜透射率能有效降低靶丸与充气管连接处的温度,在本文讨论的边界条件下,封口膜透射率大于0.025时靶丸与充气管连接处温度相对较低,晶核可维持,充气管能被堵管;而改变屏蔽罩温度及铝套筒表面发射率等做法对靶丸与充气管连接处的温度降低作用不明显,充气管无法被堵管。 相似文献
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《原子能科学技术》2020,(7)
为在冷冻靶上成功实现惯性约束核聚变点火,需在打靶前将冷冻靶丸内冰层温度降低1.5 K。针对冷冻靶快速降温过程温度场发生突变导致冰层质量恶化的问题,数值研究了快速降温过程中冷冻靶温度场的瞬态特性,并提出了优化降温方案。数值模拟基于Boussinesq假设,通过UDF编程,获得了降温速率的影响规律,并分析比较了不同延迟时间下延迟降温的数值结果。结果表明:降温开始时,最大温差急剧增大但最终趋于稳定;减小降温速率,可有效改善靶丸表面温度的均匀性,延长冰层的生存时间,使降温结束时冰层质量满足要求;具有特定延迟时间的延迟降温能改善靶丸外表面温度的均匀性从而增加冰层的生存时间,且存在最佳延迟时间使冰层的生存时间最长。 相似文献
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The pellet injection experiments for fuelling and diagnostics have been carried out on the HL-1M tokamak. The eight-pellet injector was installed on HL-1M. A reliable monitordetector and camera system was set up to take initial pellet photographs and measure the initial pellet speed and size. High fuelling efficiency of 60 % - 100 % and a density profile with a peaking factor of 1.8 - 2.0 were obtained. The maximum density close to 10^14/cm^3 in HL-1M was achieved with newly optimized combined fuelling techniques. Two typical models of pellet ablation have been utilized for simulative calculation of the ablation rates in HL-1M. In comparison with the distribution of the measured Hα emission intensity from the digital data of the CCD camera, the experimental result seems more optimistic for core fuelling than theoretical predictions by the two models. The safety factor profile q(r) has been extracted from the information provided by the CCD camera during the pellet injection. The reliability of the measured results depends mainly on the calibration of the imaging space position. Based on the calibration, the measured q-profile becomes more reasonable than those published previously for the same shot number and same photograph. 相似文献
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Heavy-ion-driven fusion (HIF) is a scheme to achieve inertial confinement fusion (ICF). Investigation of the non-uniformity of heavy-ion beam (HIB) irradiation is one of the key issues for ICF driven by powerful heavy-ion beams. Ions in HIB impinge on the pellet surface and deposit their energy in a relatively deep and wide area. Therefore, the non-uniformity of HIB irradiation should be evaluated in the volume of the deposition area in the absorber layer. By using the OK1 code with some corrections, the non-uniformityof heavy-ion beam irradiation for the different ion beams on two kinds of targets were evaluated in 12-, 20-, 60- and 120-beam irradiation schemes. The root-mean-square (RMS) non-uniformity value becomes σRMS= 8. 39% in an aluminum mono-layer pellet structure and σRMS= 6.53% in a lead-aluminum layer target for the 12-uranium-beam system. The RMS non-uniformity for the lead-aluminum layer target was lower than that for the mono-layer target. The RMS and peak-to-valley (PTV) non-uniformities are reduced with the increase in beam number, and low at the Bragg peak layer. 相似文献
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1. IntroductionHefei tokamak:7 (HT-7) is a super-conductingtokamak device which was rebuilt from the originalRussian T-7 tokamak in 1994. Recently a feedbackcontrol system to simultaneously control plasma current, density and displacement has been developedon the HT-7 and put into daily operation. HT-7with R = 1.22 m, a = 0.26 ~0.30 m has afstainless steel liner, and two immovable and two movablestainless steel liciters (including a movable liciter)with molybdenum tips. There are two layer… 相似文献
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Shigeru MORITA Motoshi GOTO Kenichi NAGAOKA Chunfeng DONG Hangyu ZHOU Zhengying CUI Yunbo DONG Xiang GAO Katsumi IDA Katsunori IKEDA Osamu KANEKO Shiyao LIN Haruhisa NAKANO Masaki OSAKABE 《等离子体科学和技术》2011,13(3):290-296
A cylindrical carbon pellet with a size of 1.2L?1.2? to 1.8L?1.8?mm and a velocity of 100 to 300 m/s was injected into Large Helical Device (LHD) for an efficient fueling based on its deeper deposition instead of hydrogen gas puffing and ice pellet injection. Electron density increment of ?ne=1014cm-3 is successfully obtained by single carbon pellet injection without plasma collapse. Typical density and temperature of the ablation plasma of the carbon pellet, e.g., 6.5x1016cm-3 and 2.5eV for CII, are examined respectively by spectroscopic method. A confinement improvement up to 50% compared to ISS-95 stellarator scaling is clearly observed in a relatively low-density regime of ne=2 to 4?1013cm-3, and high ion temperature Ti(0) of about 6keV is also observed with an internal transport barrier at ne=1.2?1013cm-3. In particular, the improvement in the ion temperature largely exceeds that observed in hydrogen gas- puffed discharges, which typically ranges below 3 keV. 相似文献
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《Journal of Nuclear Science and Technology》2013,50(11):1155-1164
For RIA-simulated experiments in the NSRR with high-burnup PWR fuel and BWR fuel, numerical analyses were performed to evaluate the temporal changes of profiles of temperature and thermal stress in pellet induced by pulse power, using the RANNS code. The pre-pulse states of rods were calculated using the fuel performance code FEMAXI-6 along the irradiation histories in commercial reactors and the results were fed to the RANNS analysis as initial conditions of the rod. One-dimensional FEM was applied to the mechanical analysis of the fuel rod, and the calculated cladding permanent strain was compared with the measured value to confirm the validity of the PCMI calculation. The calculated changes in the profiles of temperature and stress in the pellet during an early transient phase were compared with the measured data such as the internal gas pressure rise, cracks and grain structure in the post-test pellet, anddiscussed in terms of PCMI and grain separation. The analyses indicate that the pellet cracking appearances coincided with the calculated tensile stress state and that the compressive thermal stress suppresses the fission gas bubble expansion leading to grain separation. 相似文献
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《等离子体科学和技术》2014,16(10):913-918
A new pellet injection system was installed on the EAST tokamak and preliminary experiments were performed during the 2012 run campaign. Typical phenomena associated with deuterium pellet injection into a plasma discharge have been observed including sudden increases of the electron density and H α /D α emission intensity as well as a significant decrease in plasma electron temperature. Profiles have been studied in order to understand the influence of pellet fuelling on EAST discharges. Even though the injector was specifically designed for plasma fu- elling, ELM triggering using the pellet injection has also been tested. In order to find appropriate parameters for triggering ELMs in H-mode plasmas, scanning of the pellet injection speed was employed for pellets injected from both the high field side and low field side of the plasma column. It has been observed that low-speed pellets injected into H-mode plasma from the low-field side could trigger an ELM followed by a number of smaller induced ELMs at about 300 Hz. 相似文献
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Electrothermal mass accelerators, based on capillary discharges, that form a plasma propelling force from the ablation of a low-z liner material are candidates for fuelling magnetic fusion reactors. As lithium is considered a fusion fuel and not an impurity, lithium hydride and lithium deuteride can serve as good ablating liners for plasma formation in an electrothermal plasma source to propel fusion pellets. A comprehensive study of solid lithium hydride and deuteride as liner materials to generate a plasma to propel cryogenic fuel pellets is presented here. This study was conducted using the ETFLOW capillary discharge code. Relationships between propellants, source and barrel geometry, pellet volume and aspect ratio, and pellet velocity are determined for pellets ranging in volume from 5 to 100 mm3. 相似文献
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Dahlburg Jill P. Gardner John H. Schmitt Andrew J. Obenschain S. P. 《Journal of Fusion Energy》1998,17(3):227-229
There are several topics that require resolution prior to the construction of an Inertial Fusion Energy [IFE] laboratory Engineering Test Facility [ETF]: a pellet that produces high gain; a pellet fabrication system that cost-effectively and rapidly manufactures these pellets; a sufficiently uniform and durable high repetition-rate laser pellet driver; a practical target injection system that provides accurate pellet aiming; and, a target chamber that will survive the debris and radiation of repeated high-gain pellet implosions. In this summary we describe the science issues and opportunities that are involved in the design of a successful high gain direct drive Inertial Confinement Fusion [ICF] pellet. 相似文献
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The thermal and mechanical behavior of fuel rods is significantly influenced by the extent of their relocation and by compliance of the cracked pellets. Movement of the cracked pellet pieces towards the cladding results in softer pellets with crack voids which accommodate some fraction of the thermoelastic pellet deformation and make the pellet more compliant under the restraint of the cladding. It is difficult to model such a pellet compliance independently of experimental observations because the cracked pellet behavior is uncertain by nature.Electrically heated simulation of pellet-cladding mechanical interaction (PCMI) facilitates much quicker and more flexible experimentation than actual in-pile tests. Testing apparatus consists of the simulated fuel rod with hollow UO2 pellets and a tungsten rod in the center, and a diameter measuring device including three pairs of diameter sensors. Test parameters include the pellet-cladding gap and the cladding thickness. Results show that rods with a smaller gap have a larger increasing rate of cladding diameter. This suggests that a group of cracked pellet pieces induced by thermal stress has an apparent compliance which increases with pellet-cladding gap. Results also show more sensitivity to cladding thickness than those calculated assuming pellets having intrinsic stiffness. This also suggests the compliant nature of cracked pellets.Such a compliant nature can almost be described by reducing the elasticity of the pellet. A simple pellet compliance model was obtained by fitting calculations with measurements to describe a cracked pellet as a uniform axisymmetric body with apparent elasticity. 相似文献