A vertical test system for China-ADS project injector Ⅱ superconducting cavities

To test superconducting cavities, a vertical test system has been designed and set up at the Institute of Modern Physics (IMP). The system design is based on VCO-PLL hardware and the NI Labview software. The test of the HWR010#2 superconducting cavity shows that the function of this test system is satisfactory for testing the low frequency cavity.     

Imaginary Part of the Surface Tension of Water

We report a direct measurement of the imaginary part of the surface tension of water through a dynamic scheme using a thin vertical glass fiber of diameter of 3 tun with one end glued onto a cantilever beam and the other end touching a water-air interface. The frequency dependence of the dissipation factor experienced by the glass fiber is exactly calculated through measuring the phase delay with various frequencies when the glass fiber is forced to oscillate vertically. We find the same intercept at the dissipation factor axis for different frequency dependences of the dissipation factor for different depths by which the glass fiber is dipped into water. This nonzero dissipation factor at zero frequency presents direct evidence of the existence of the imaginary part of surface tension of water and yields a complex surface tension of water σ^＊ = 0.073 ＋ i（0.017 ± 0.002） N/m at room temperature.     

基于纳米金自组装膜固定辣根过氧化物酶的生物传感研究

将辣根过氧化物酶(HRP)通过纳米技术和自组装技术固定于电极表面,制得了酶修饰电极.纳米金与HRP形成了静电复合物并高效地保持了HRP的生物活性,以对苯二酚作为电子媒介体,差示脉冲伏安法(DPV)研究生物酶电极测定H2O2的线性范围为5.0×10-6～1.0×10-3 mol/L,检测限为2.5×10-6 mol/L,线性方程为△I=0.34765+4.05553CH2O2(mM).酶电极的表观米氏常数(K(app))为0.0675 mmol/L.实验同时证明该生物酶电极具有良好的稳定性和使用寿命.     

降温速率对Ag-SmBCO单畴生长中自发成核的影响

在前期的研究中曾通过Ag掺杂降低Sm123/Sm211体系熔点,利用Nd123冷籽晶技术成功制备出具有理想织构的SmBCO/Ag单畴块材.但在实验结果中发现相比于未掺杂坯体,掺入Ag后的SmBCO坯体生长速率下降,在所考察的慢冷温区里,生长速率呈不断减小趋势,最终因自发成核而无法继续生长,使得SmBCO单畴区域局限于15×15mm2范围内.为了抑制单畴生长中的自发成核现象,本文研究了降温速率对SmBCO/Ag单畴自发成核的影响.在两组不同条件下的降温速率实验中发现,不同的降温速率对体系自发成核的抑制效果是不同的.利用降低降温速率,成功地将掺Ag SmBCO单畴面积从15×15mm2增大至26×26mm2.     

同质冷籽晶技术生长SmBCO/Ag超导单畴块材的研究

在前期的研究中,利用NdBCO123冷籽晶技术成功制备出具有理想织构的SmBCO/Ag单畴块材.但由于高质量的Nd籽晶的供应难以得到保证,从而限制了SmBCO单畴块材的批量化制备.Ag可以降低SmBCO坯体的熔点,这为用SmBCO冷籽晶技术引导SmBCO/Ag坯体生长单畴块材提供了可能性.然而,实验中我们发现,坯体里面的Ag容易向籽晶内部扩散,导致籽晶熔融,对单畴块材的生长产生不利影响.为克服这困难,我们通过在坯体和籽晶之间加入一个SmBCO211缓冲层,有效地阻止坯体里面的Ag向籽晶扩散,成功实现了同质冷籽晶技术生长SmBCO超导单畴块材.     

ErP5O14非晶玻璃的红外量子剪裁

研究了Er_1.0P₅O₁₄铒非晶玻璃的红外量子剪裁现象. 从吸收谱和激发光谱的计算比较中肯定了Er_1.0P₅O₁₄非晶 玻璃的1537.0 nm红外荧光为多光子量子剪裁荧光. 从Er_1.0P₅O₁₄非晶玻璃的可见和红外荧光发射光谱中发现激发²H_11/2, ⁴G_11/2和⁴G_9/2能级所导致的⁴I_13/2→⁴I_15/2量子剪裁红外荧光很强;基于自发辐射速率、无辐射弛豫速率和能量传递速率等参数的计算,对其量子剪裁机理进行了分析.发现起源于基态的强下转换能量传递{²H_11/2→⁴I_9/2,⁴I_15/2→⁴I_13/2},{⁴G_11/2→⁴I_13/2, ⁴I_15/2→²H_11/2},{⁴G_9/2→⁴F_7/2,⁴I_15/2→⁴I_13/2}和{⁴G_9/2→⁴I_13/2, ⁴I_15/2→²H_11/2}是导致Er_1.0P₅O₁₄非晶玻璃具有强的三光子和四光子量子剪裁红外荧光的原因.研究结果对改善太阳能电池效率有一定意义.     

水泵水轮机开机过程压力脉动的试验研究

水泵水轮机机组的压力脉动是影响机组稳定性的一个非常重要的因素,而转轮与活动导叶之间的无叶区的压力脉动具有振幅最大、振源复杂的特点。本文通过某抽水蓄能电站的真机的试验数据分析,对机组开机过程中无叶区的压力脉动进行了较为深入的研究,获得了水轮机的开机过程及水泵的开机过程中无叶区的压力脉动的幅值和频谱特性,并对其特点进行了分析。     

不同X射线管电压下CsI和CsI(Tl)晶体的X射线辐照致发光

在室温(290 K)和低温(25 K)下,测量了从11～40 kV的一系列管电压下X射线激发纯CsI和CsI (Tl)晶体的辐照致发光(RL)谱.结果表明:在固定温度下,管电压变化后, 305 nm和340 nm的本征发光带和580 nm的非本征发光带的形状结构均不发生变化,只是其强度发生变化.对所测得的各发光带强度随管电压的变化关系用抛物线模型进行了拟合分析,得到了较好的结果.同时还发现纯CsI和CsI (Tl)晶体中所有本征RL发光带强度与X射线强度基本上成正比关系,而当管电压增加时,CsI (Tl)晶体中非本征发光带强度的增加速度慢于本征发光带.分析认为,290 K时这可能与样品中另一个位于400 nm左右的发光带有关;而在25 K时则可能和H心与VK心的竞争有关.     

PLE spectra analysis of the sub-structure in the absorption spectra of CdSeS quantum dots

The semiconductor CdSeS quantum dots (QDs) embedded in glass are analysed by means of absorption spectra, photoluminescence (PL) spectra and photoluminescence excitation (PLE) spectra. The peaks of absorption spectra shift to lower energies with the size of QD increasing, which obviously shows a quantum-size effect. Using the PLE spectra, the physical origin of the lowest absorption peak is analysed. In PLE spectra, the lowest absorption peak can be deconvoluted into two peaks that stem from the transitions of 1S_3/2--1S_e and 2S_3/2--1S_e respectively. The measured energy difference between the two peaks is found to decrease with the size of QD increasing, which agrees well with the theoretical calculation for the two transitions. The luminescence peak of defect states is also analysed by PLE spectra. Two transitions are present in the PLE, which indicates that the transitions of 1S_3/2--1S_e and 2S_3/2--1S_e are responsible for the defect states luminescence.     

隔水套管波流联合作用下非线性动力响应

考虑流及波流联合作用,研究了深水套管的涡激非线性振动．将套管简化为梁模型,计及Morison非线性流体动力和涡激荷载,建立套管的涡激振动方程．采用Korolov函数求解套管的固有频率和模态,提出了计算涡激非线性动力响应的Galerkin方法,计算了160 m水深中170 m长套管的固有频率和模态,研究了流引起的主共振和波流联合引起的组合共振．计算结果表明波流联合作用下套管的动力响应明显增大,结果也揭示了波流联合激励下套管复杂的动力响应特性．