原子储存泡技术是氢微波激射器(氢脉泽)的关键技术。传统的石英薄壁储存泡位于TE011模的空心圆柱谐振腔的中心。为了缩小氢脉泽谐振腔和原子储存泡的体积采用了蓝宝石加载谐振腔取代传统的腔泡结构,并将蓝宝石晶体的内壁作为原子储存泡...原子储存泡技术是氢微波激射器(氢脉泽)的关键技术。传统的石英薄壁储存泡位于TE011模的空心圆柱谐振腔的中心。为了缩小氢脉泽谐振腔和原子储存泡的体积采用了蓝宝石加载谐振腔取代传统的腔泡结构,并将蓝宝石晶体的内壁作为原子储存泡,分析了脉泽工作状态的变化。为了消除蓝宝石加载腔的腔频率随温度的敏感变化(-60 k Hz/K)对脉泽自激振荡频率相对大的牵引效应,在蓝宝石加载谐振腔中再加载具有负介电常数温度系数的钛酸锶晶体,将腔频率温度系数近似地补偿到零。实现了采用介质加载谐振腔的氢脉泽的自激振荡,并通过锁相环实现氢脉泽对晶体振荡器的控制而形成稳定的频率源,短期稳定度指标在量级上达到了主动型氢原子钟(氢钟)的指标(1 000 s稳定度达1.5×10-14)。展开更多
TN24 98010139关于改型斜旋转轴对称准光腔自由电子微波激射器的一个注记=Addendum to the study of free electronmaser with modified axisymmertrical quasiopticalcavity of oblique rotation[刊,中]/刘濮鲲(北京大学技术物理系,重...TN24 98010139关于改型斜旋转轴对称准光腔自由电子微波激射器的一个注记=Addendum to the study of free electronmaser with modified axisymmertrical quasiopticalcavity of oblique rotation[刊,中]/刘濮鲲(北京大学技术物理系,重离子物理研究所.北京(100871)),杨中海,刘盛纲(电子科技大学高能电子学研究所.四川,成都(610054))//光学学报.-1997,17(6).-677-680对作者先前在改型斜旋转轴对称准光腔(MAQCOR)自由电子微波激射器方面的工作进行了补充,说明改型斜旋转轴对称准光腔回旋微波激射器还有一个重要的优点,即可以通过适当选择旋转角把电子注热发散对注-波互作用的不利影响降至最小。展开更多
Extremely hard and abrasive rocks pose great challenges to the past and ongoing TBM projects by increasing cutter wear and reducing penetration rates.A considerable amount of research has been conducted to improve the...Extremely hard and abrasive rocks pose great challenges to the past and ongoing TBM projects by increasing cutter wear and reducing penetration rates.A considerable amount of research has been conducted to improve the performance of TBMs in those challenging grounds by either improving the capacity of TBMs or developing assisting rock breakage methods.This paper first highlights the challenges of hard and abrasive rocks on TBM tunneling through case studies.It then presents the development of hard rock TBMs and reviews the technologies that can be used individually or as assistance to mechanical excavators to break hard rocks.Emphases are placed on technologies of high pressure waterjet,laser and microwave.The state of the art of field and laboratory research,problems and research directions of those technologies are discussed.The assisting methods are technically feasible;however,the main challenges of using those methods in the field are that the energy consumption can be over 10 times high and that the existing equipments have robustness problems.More research should be conducted to study the overall energy consumption using TBMs and the assisting methods.Pulsed waterjet,laser and microwave technologies should also be developed to make the assistance economically viable.展开更多
文摘原子储存泡技术是氢微波激射器(氢脉泽)的关键技术。传统的石英薄壁储存泡位于TE011模的空心圆柱谐振腔的中心。为了缩小氢脉泽谐振腔和原子储存泡的体积采用了蓝宝石加载谐振腔取代传统的腔泡结构,并将蓝宝石晶体的内壁作为原子储存泡,分析了脉泽工作状态的变化。为了消除蓝宝石加载腔的腔频率随温度的敏感变化(-60 k Hz/K)对脉泽自激振荡频率相对大的牵引效应,在蓝宝石加载谐振腔中再加载具有负介电常数温度系数的钛酸锶晶体,将腔频率温度系数近似地补偿到零。实现了采用介质加载谐振腔的氢脉泽的自激振荡,并通过锁相环实现氢脉泽对晶体振荡器的控制而形成稳定的频率源,短期稳定度指标在量级上达到了主动型氢原子钟(氢钟)的指标(1 000 s稳定度达1.5×10-14)。
文摘TN24 98010139关于改型斜旋转轴对称准光腔自由电子微波激射器的一个注记=Addendum to the study of free electronmaser with modified axisymmertrical quasiopticalcavity of oblique rotation[刊,中]/刘濮鲲(北京大学技术物理系,重离子物理研究所.北京(100871)),杨中海,刘盛纲(电子科技大学高能电子学研究所.四川,成都(610054))//光学学报.-1997,17(6).-677-680对作者先前在改型斜旋转轴对称准光腔(MAQCOR)自由电子微波激射器方面的工作进行了补充,说明改型斜旋转轴对称准光腔回旋微波激射器还有一个重要的优点,即可以通过适当选择旋转角把电子注热发散对注-波互作用的不利影响降至最小。
基金Projects(3205009419,3205002001C3)supported by Fundamental Research Funds for Central Universities,China。
文摘Extremely hard and abrasive rocks pose great challenges to the past and ongoing TBM projects by increasing cutter wear and reducing penetration rates.A considerable amount of research has been conducted to improve the performance of TBMs in those challenging grounds by either improving the capacity of TBMs or developing assisting rock breakage methods.This paper first highlights the challenges of hard and abrasive rocks on TBM tunneling through case studies.It then presents the development of hard rock TBMs and reviews the technologies that can be used individually or as assistance to mechanical excavators to break hard rocks.Emphases are placed on technologies of high pressure waterjet,laser and microwave.The state of the art of field and laboratory research,problems and research directions of those technologies are discussed.The assisting methods are technically feasible;however,the main challenges of using those methods in the field are that the energy consumption can be over 10 times high and that the existing equipments have robustness problems.More research should be conducted to study the overall energy consumption using TBMs and the assisting methods.Pulsed waterjet,laser and microwave technologies should also be developed to make the assistance economically viable.
