兰州大学强流D-D/D-T中子发生器

兰州大学中子应用技术教育部工程研究中心着力发展倍压型加速器聚变中子源和紧凑型加速器聚变中子源，建立先进完备的快中子监测系统及用于开展快中子物理研究的测量设备，建成国内一流的聚变中子学研究实验室。兰州大学中子应用技术教育部工程研究中心自主研制的强流D-D/D-T中子发生器，D-T快中子产额可达10¹²n/s量级，D-D快中子产额可达10¹⁰n/s量级。

兰州大学中子应用技术教育部工程研究中心自主研发的10¹⁰n/s、10¹¹n/s和10¹²n/s中子发生器先后获得了甘肃省科学大会奖、国家教委科技进步一等奖、国家科技进步三等奖、甘肃省教委科技进步贰等奖等。

近年来，随着国际国内新型核能系统的研发对中子物理的高要求以及中子应用技术在工业、农业、环境、地质方面的发展趋势，本所在未来一段时期将重点开展以下方面的研究：（1）研发更高产额的强流中子发生器，开展中子物理与中子应用技术的基础研究工作；（2）研发适用于工业现场应用的紧凑型长寿命加速器中子源，开展中子应用技术的产学研发展；（3）针对新型核能系统，开展中子诱发长寿命锕系核素裂变物理的研究；（4）发展快中子、热中子成像技术，开发中子成像系统；（5）开展中子生物育种、中子测井、中子活化分析等方面的研究。

此外，该中心建设有倍压型加速器、中子测量系统、离子源研发平台、高压电源实验平台和低本底γ实验装置，能够为强流D-D/D-T中子发生器的研制、运行、维护提供技术保障和测量服务。

High Intensity D-D/D-T Neutron Generator at Lanzhou University

Engineering Research Center for Neutron Application Technology (ERCNAT) has devoted efforts to developing fusion neutron source and compact accelerator fusion neutron source, establishing advanced and complete fast neutron monitoring system and measuring equipment for researches of fast neutron physics, and establishing a first-class fusion neutron research laboratory in China. The independent development of high intensity D-D/D-T neutron generator from ERCNAT, the neutron yields up to 10¹²n/s for D-T fast neutron generator and 10¹⁰n/s for D-D fast neutron generator.

The neutron generators which the yields respectively are 10¹⁰n/s, 10¹¹n/s and 10¹²n/s, independently developed by the ERCNAT, have successively won the award of Gansu science, first prize for scientific and technological progress of the state education commission, the third award of the state scientific and technological progress and second prize for scientific and technological progress of Gansu education commission, etc.

In recent years, with the high demand for neutron physics and the development trend of neutron application technology in industry, agriculture, environment and geology in the research and development of new nuclear energy systems, our institute will focus on the following aspects in the future: (1) Researches and developments of high intensity neutron generator with higher yield and basic research on neutron physics and neutron application technology (2) Researches and development of neutron source in compact long-life accelerator for industrial field application and development of neutron application technology (3) Researches on fission physics of neutron-induced long-lived actinide nuclides for a new type of nuclear energy system (4) Development of fast neutron and thermal neutron imaging technology and neutron imaging system (5) Researches on neutron breeding, neutron logging and neutron activation analysis.

Moreover, the center possessed Cockcroft-Walton electron accelerator, the system of neutron measurement, research and development platform of ion source, high voltage power supply experimental platform and experimental device of low background gamma measurement. And it can provide technical support and measurement services for the development, operation and maintenance of high intensity D-D/D-T neutron generator.

图1. 兰州大学强流D-D/D-T中子发生器

Fig.1 High Intensity D-D/D-T Neutron Generator at Lanzhou University

兰州大学紧凑型D-D/D-T中子发生器

紧凑型D-D/D-T中子发生器是开发小型化中子照相、中子活化分析系统的关键设备，在核材料检测、航空航天元件无损检测（如航空发动机叶片、航天器）、反恐核查等方面有重要的应用价值。

兰州大学中子应用技术教育部工程研究中心通过研究氘氚（D-T）、氘氘（D-D）和氘铍（D-Be）反应加速器中子源特性，掌握先进离子源选型、离子束引出及加速系统设计、靶系统设计、二次电子抑制系统设计等关键技术问题，自主研发了一款多用途、能产生多种能量中子（D-T中子、D-D中子和D-Be中子）的紧凑型中子发生器。目前，该装置为国内首台紧凑型中子发生器。

该紧凑型中子发生器具有可移动、能拆卸和方便维修、使用寿命长等优点。特别是紧凑型D-D或D-Be中子发生器，可采用自注入靶模式或金属Be靶，靶寿命长，成本低，且不涉及核材料及放射性氚靶，有更好的安全性。该紧凑型中子发生器长度仅为1.0m，直径小于25cm，适用于计量站所、工业现场、海岸关口等场所，为基于紧凑型中子发生器的中子活化分析、快中子照相、中子爆炸物检测在民用领域的广泛应用准备条件。

Compact D-D/D-T Neutron Generator at Lanzhou University

Compact D-D/D-T neutron generator is the key equipment for developing miniaturized neutron radiography and neutron activation analysis system. It has important application value in nuclear material testing, non-destructive testing of aerospace components (such as, blade of aviation engine, spacecraft ), anti-terrorism verification, etc.

By studying the characteristics of neutron sources in D-T, D-D and D-Be reaction accelerators, the Engineering Research Center for Neutron Application Technology (ERCNAT) has mastered the key technical issues of advanced ion source selection, ion beam extraction, acceleration system design, target system design and secondary electron suppression system design. ERCNAT also developed a multi-purpose compact neutron generator for neutrons (D-T neutrons, D-D neutrons and D-Be neutrons) independently which can produce neutrons of many energies. At present, it is the first compact neutron generator in China.

The compact neutron generator has the advantages of movability, disassembling, maintenance-friendly and long service life. In particular, compact D-D or D-Be neutron generator has long life and low cost which can adopt self-injection target mode or metal Be target Furthermore, it does not involve with nuclear materials and radioactive tritium target, so it has better safety. It is only 1.0m in length and less than 25cm in diameter. As a result, it is suitable for measuring stations, industrial field, coastal crossings and other places. It is a preparation for the wide application of neutron activation analysis, fast neutron photography and neutron explosive detection in civil fields.

图2. 兰州大学紧凑型D-D/D-T中子发生器

Fig.2 Compact D-D/D-T Neutron Generator at Lanzhou University

加速器中子源中子辐射场评价

兰州大学中子应用技术教育部工程研究中心提出了Multi-layer模型，开展D-D、D-T、D-Be加速器中子源的中子辐射场分布研究，评价加速器中子源的产额分布、能谱分布、角产额分布，将为中子物理研究和中子应用技术研究提供精确的场分布数据和场分布模型。

目前，采用Multi-layer模型评价了氘离子轰击氘钛靶(TiD_x)、氚钛靶(TiT_x)和厚金属铍(Be)靶发生(d,n)反应产生的中子辐射场分布。计算得到了氘束能量小于E_d=1.0 MeV范围内，厚靶D-D和D-T反应加速器中子源的中子产额、能谱和角分布数据；计算得到了氘束能量在E_d=0.5-20.0 MeV范围内，厚靶D-Be反应加速器中子源的中子产额、能谱和角分布数据。

Evaluation on Neutrons Distributions for Accelerator-based Neutron Source

Engineering Research Center for Neutron Application Technology (ERCNAT) has developed Multi-layer model to evaluate neutrons distributions for accelerator-based D-D, D-T and D-Be neutron sources, including neutron yields, neutron energy distributions and neutron angular distributions. This work can provide accurate neutron field distributions data and neutron field distributions model for neutron physics and neutron application technology.

Neutron energy spectrum, angular distribution, and integrated yield of ²H(d,n)³He and ³H(d,n)⁴He reaction with deuteron-energy lower than 1.0 MeV are calculated by the Multi-layer model. The integrated neutron yield of ²H(d,n)³He or ³H(d,n)⁴He neutron source changes along with increasing deuteron energy. There are also different integrated neutron yields for TiD_xor TiT_x targets. Moreover, neutron energy spectrum of ²H(d,n)³He or ³H(d,n)⁴He neutron source with widening distributions are different for different neutron emission-angle. The Multi-layer model is also developed to calculate the neutron energy spectrum, angular distribution, and integrated yield of the ⁹Be(d,xn) reaction on a thick beryllium target as an accelerator-based neutron source in the incident-deuteron-energy range from 0.5 to 20.0 MeV. Typical computational results are presented, and are compared with the previous experimental data to evaluate the computing model as well as the characteristics of the ⁹Be(d,xn) reaction with a thick Be target.

  

图3. 厚靶D-D/D-T加速器中子源中子积分产额分布

Fig.3 Neutron yields for accelerator-based D-D/D-T neutron sources

  

图4. 厚靶D-D/D-T加速器中子源中子能谱分布@Ed=400 keV

Fig.4 Neutron energy distributions for accelerator-based D-D/D-T neutron sources

  

图5. 厚靶D-D/D-T加速器中子源中子角产额分布

Fig.5 Neutron angular distributions for accelerator-based D-D/D-T neutron sources 

   

图6. 厚靶D-Be加速器中子源中子积分产额分布

Fig.6 Neutron yields for accelerator-based D-Be neutron sources

图7. 厚靶D-Be加速器中子源中子能谱分布@Ed=7.0, 13.5, 17.0, 20.0 MeV

Fig.7 Typical neutron energy distributions for accelerator-based D-Be neutron sources

图8. 厚靶D-Be加速器中子源中子角产额分布

Fig.8 Neutron angular distributions for accelerator-based D-Be neutron sources

 

姚泽恩 教授

兰州大学中子应用技术教育部工程研究中心

E-mail：zeyao@lzu.edu.cn