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强流电子束二极管是强脉冲辐射环境模拟装置和高功率微波技术中的重要研究方向,通过时间分辨光谱诊断研究阴极等离子体的特性是分析强流脉冲电子束二极管工作性能的可靠方法之一。介绍了具有纳秒级时间分辨能力的光谱诊断系统及其工作原理、系统组成和性能参数,并阐述了低抖动同步触发系统的实现方法和时序关系。同时,针对强脉冲辐射模拟装置产生的强脉冲电磁辐射和强X、γ射线辐射对光谱诊断系统造成严重干扰的情况,设计了电磁屏蔽室和铅屏蔽室对诊断系统进行保护。对黄铜阴极的等离子体进行时间分辨光谱测量,实验结果表明,随着二极管脉冲电压和电流的上升,参与形成阴极等离子体的元素和物质成分明显增多。该光谱诊断系统的时间分辨能力为10 ns,最小可达2 ns,同步触发系统的抖动小于4.0 ns,为深入研究二极管的阴极发射机理开辟了新的技术途径。 相似文献
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常压低温等离子体的消毒灭菌作为一种新型的消毒方法,由于其具有安全、简便、低温和快速等优点,正日益受到人们的重视和研究。文章综述了常压低温等离子体消毒灭菌的研究进展,包括了实验装置、实验条件及消毒灭菌机理,还介绍它在环境工程、食品加工等方面的应用前景。 相似文献
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惯性约束核聚变研究最近取得可喜成果,美国国家点火装置NIF装置实验上聚变增益达到了输入激光能量的三分之二.但是,这一成果与人们的预期还有较大差距,需要更深入研究激光与等离子体相互作用初期的动力学过程.我们发展了一种新方法,用单发长脉冲电子束团为探针,测量激光等离子体内电磁场在整个等离子体持续时间内的演化过程.实验中,高压静电电子源产生能量0—100 keV连续可调、脉宽10ns的电子束团.1 J,532 nm,脉宽约4 ns的激光脉冲聚焦到银靶上,激发产生等离子体.电子束团穿过激光等离子体,被其中的电磁场调制后成像,单发电子束团时间宽度会覆盖整个等离子体持续时间,通过分析电子束团的调制强度,推得等离子体内电磁场的变化.实验上成功实现了单发电子束团对整个激光等离子体内电场的诊断测量,获得了演化曲线,推算出实验条件下电子束通过路径上平均电场的最大值约为7.74×10~5 V/m. 相似文献
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利用强流脉冲电子束(HCPEB)装置对多晶纯镍进行轰击,采用X射线衍射及扫描电子显微镜等技术,详细分析了受轰击样品的变形组织与结构。通过分析建立了强流脉冲电子束诱发的应力特征与变形结构之间的关系,并对目前现有的几种应力波数值模拟结果进行了讨论。实验结果表明:强流脉冲电子束能够在材料表层诱发约5GPa的应力,造成纯镍表面发生孪生塑性变形。除了热膨胀引起的表层横向准静态热应力外,强流脉冲电子束产生的等离子体脉冲爆炸可以直接诱发幅值很高的冲击应力波,二者的共同作用是引起表层微观结构变化的直接原因。 相似文献
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Prospects and application of ultrasound and magnetic fields in the fermentation of rare edible fungi
Ultrasound has the potential to be broadly applied in the field of agricultural food processing due to advantages such as environmental friendliness, low energy costs, no need for exogenous additives and ease of operation. High-frequency ultrasound is mainly used in medical diagnosis and in the food industry for the identification of ingredients and production line quality testing, while low-frequency ultrasounds is mainly used for extraction and separation, accelerating chemical reactions, auxiliary microbial fermentation and quality enhancement in food industry. Magnetic fields have many advantages of convenient use, such as non-toxic, nonpolluting and safe. High-intensity pulsed magnetic fields are widely used as a physical non-thermal sterilization technology in food processing, while weak magnetic fields are better at activating microorganisms and promoting their growth. Ultrasound and magnetic fields, due to their positive biological effects, have a wide range of applications in the food processing industry. This paper provides an overview of the research progress and applications of ultrasound and magnetic fields in food processing from the perspectives of their biological effects and mechanisms of action. Additionally, with the development and application of physical field technology, physical fields can now be used to provide significant technical advantages for assisting fermentation. Suitable physical fields can promote the growth of microbial cells, improve mycelial production and increase metabolic activity. Furthermore, the current status of research into the use of ultrasound and magnetic field technologies for assisting the fermentation of rare edible fungi, is discussed. 相似文献
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《Current Applied Physics》2010,10(4):1164-1168
Bio-applications of atmospheric pressure plasma have been widely studied in recent years. However, the devitalization mechanisms of micro-organisms by atmosphere pressure plasma have not been clearly explained. This paper was to find the possible sterilization mechanisms and define the major sterilization factors with the atmospheric pressure plasma jet. For the sterilization target, the Bacillus subtilis was selected. In this paper, a set of physical or chemical methods were used to characterize the following sterilization factors: heat, ultraviolet radiation, charged species and chemical reactive species generated by the plasma. It was found that the bacterial inactivation efficacy had a significant improvement when oxygen was introduced into the plasma jet system. Comparing with the result of sterilization, the inactivation process was dominantly controlled by synergistic actions of chemically active species and charged species, rather than heat, or ultraviolet radiation. 相似文献
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气相过氧化氢为强氧化剂,其消毒、灭菌的最终产物为水和氧气,具有无残留、安全、快速消毒以及广泛的材料兼容性等优点。广泛应用于制药、医疗、卫生、生物安全等领域,特别是新冠肺炎、MERS、SARS以及甲流等呼吸类传染性疾病的消毒防治。为保证灭菌效果,防止无菌检查的假阴性或者假阳性,需要对过氧化氢的浓度进行监测。基于1 255 cm-1量子级联激光器可调谐激光吸收光谱技术研制了一套气相过氧化氢浓度测量装置,浓度测量范围为0~1 800 ppm。采用V型光路结构、窗口片将检测仪主要部件与过氧化氢进行隔离,避免过氧化氢腐蚀。针对高浓度、高吸光度时一阶泰勒级数近似透射率函数误差较大这一情况,采用二阶泰勒级数近似透射率函数,导出了二次谐波信号关于气体浓度的二次函数。二次谐波信号测得是电压值,采用高锰酸钾滴定法对其进行标定、溯源。最终得到气相过氧化氢浓度的测量公式,对高低浓度过氧化氢都拟合较好,拟合误差最大为3%。当湿度变化时,二次谐波信号没有发生变化,排除水分对过氧化氢测量的影响,适用于灭菌过程中常压下高浓度VHP的浓度测量。 相似文献
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研制了一套单极性微秒脉冲阵列式等离子体射流系统,该系统可在大气压下激发产生等离子体射流,实现大面积的灭菌处理。该系统可产生峰值电压20 kV、频率15 kHz的高压脉冲,激发产生的射流均匀稳定,覆盖面积达37.7 cm2,射流长度达6 cm,射流功率为40.05 W,处理5 min可使射流覆盖范围内的枯草芽孢杆菌的芽孢基本全部失去活性。考察了不同参数对灭菌效率的影响,结果表明,灭菌率与工作电压、脉冲频率、处理时间呈正相关,在氦气氛围下有较好的灭菌效果。SEM显示等离子体射流能够对枯草芽孢杆菌的芽孢外壳结构造成损坏,导致芽孢无法正常代谢,最终死亡。 相似文献
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液相等离子体是冷等离子体的一个新分支,具有温度低、传质传热快、常压操作、反应活性高等特点。基于液相等离子体的过程强化技术在纳米材料制备、挥发性有机物降解、杀菌消毒、化学合成等领域有广泛的应用前景。以液相等离子体中纳米材料的制备为研究对象,介绍了反应体系可能存在的活性粒子、检测方法和反应机理;对常见的反应器结构进行归纳整理,按照放电是否在电解液内部进行将其分为非浸没式和浸没式液相等离子体两大类,并列举了几种典型的反应器结构;介绍了几类利用液相等离子体技术制备纳米材料的典例,并对该领域的研究现状做了总结;对该领域亟需解决的问题与发展方向进行讨论与展望。 相似文献
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Kotov Y.A. Sokovnin S.Y. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》2000,28(1):133-136
Problems concerning the use of nanosecond electron beams for sterilization of hermetically packed objects, and powdered or granulated materials, are discussed. The advantages and disadvantages of this type of radiation sterilization are demonstrated. The results are of interest to researchers who study the mechanism by which nanosecond electron beams act on microorganisms. It is worth considering repetitively pulsed electron accelerators as highly promising systems for use in commercial sterilization applications. Technologies and setups for the radiochemical sterilization (RCS) of medical glassware for blood products, beer bottles, bone meal used in food industry, medical instruments (surgical needles, systems for human kidneys), and of the external packaging for some biological materials used in ophthalmology are discussed. Such applications have been developed based on the use of the URT-0.2 and URT-0.5 repetitively nanosecond-pulsed electron accelerators. The observed sterilization of areas shaded from line-of-site irradiation and of the bottoms of, for example, glassware cannot be attributed to radiation sterilization alone, since the glass thickness was much larger than the range of electrons. Therefore, it can be conjectured that the demonstrated sterilization effect is due both to the electron beam and to the ozone and chemical radicals produced by the beam. Thus, one may introduce the notion of RCS 相似文献
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大气压等离子体羽放电产生的低温等离子体由于不需要真空装置,可以对复杂材料进行三维处理等,在工业上具有广泛的应用前景。本工作利用等离子体针放电装置在大气压空气中产生了稳定的等离子体羽。通过光谱测量,发现等离子体羽发射谱中存在777.5和844.6nm的氧原子谱线。这表明在大气压空气放电中产生了具有高化学活性的氧原子。通过光谱学方法研究了氧原子谱线强度的空间分布,发现靠近电极处氧原子谱线强度远大于其他位置。为了对这一现象进行解释,利用光电倍增管对等离子体羽的发光信号进行了空间分辨测量,发现靠近电极处发光信号宽度远大于其他位置的发光信号宽度。这些结果对大气压空气等离子体羽在杀菌消毒等领域的应用具有重要意义。 相似文献
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Since fecal coliforms was introduced as a standard indicator of pollutants in effluents of municipal wastewater treatment plants in China in 2003, chlorine had been widely used in many wastewater treatment plants. However, concerns about the disinfection by-products (DBPs) of chlorine have been increasing. One of the effective way to reduce the production of DBPs is to reduce the effective chlorine dosage by improving the utilization rate of disinfectant. Ultrasound (US) is proved to be effective in wastewater treatment for its multiple chemical and physical effects produced by cavitation, which could favor the disinfection process accordingly. For the purpose of improving disinfection efficiency with the help of US, following points are addressed in the current study: (1) investigate the enhancement effects of US on the disinfection efficiency of sodium hypochlorite (NaClO) for real secondary effluents of municipal wastewater treatment plants; (2) evaluate the possibility of using US specific energy consumption (kJ/L) as an parameter for disinfection efficiency evaluation; and (3) quantify the reduction in chlorine-DBPs through US application. Results demonstrated that sonication could reduce two-thirds (US pretreatment) or one-third (simultaneous US and NaClO disinfection) of the required concentrations of NaClO (available chlorine) for 4 log reduction of fecal coliforms, which could meet the Class 1A (fecal coliforms less than 1000 CFU/L) discharge standard of China. In addition, US pretreatment with NaClO disinfection performed better enhancement in disinfection efficiency compared with simultaneous US and NaClO disinfection. Furthermore, analysis on DBPs showed that US application as pretreatment could obviously reduce the contents of trichloromethane (TCM) and trichloroacetic acid (TCAA) by more than 85% and 50%, respectively, compared with NaClO disinfection alone for the same disinfection efficiency. Meanwhile, the experimental results also showed that the disinfection efficiency and DBPs concentration were only slightly affected under a constant US specific energy consumption, although input power density and irradiation time changed, indicating that specific energy consumption (kJ/L) could be considered as a better control parameter for disinfection efficiency evaluation. 相似文献