与太阳电池研究相适配的双原点坐标系

光生电流是太阳电池电流方程中的一个关键数值,但在单原点坐标系中无法进行标示,因此设计了双原点坐标系.在双原点坐标系中,通过对基尔霍夫电流定律如何进行标示的讨论,实现了太阳电池等效电路中各电流项和电压项的标示.双原点坐标系清晰地指出:光生电流与短路电流之差随短路电流增大而增大,只有在低光照下光生电流与短路电流才大致相当,在高光照下两者差异不可忽略;太阳电池输出功率与内耗功率在光生电流总功率中的占比随光生电流会发生改变,若要求输出功率大于内耗功率,则太阳电池不宜工作在高光照下.双原点坐标系为太阳电池的研究提供了一个适配的坐标系.     

分数阶傅里叶变换结合高峰均比抑制算法对CO-OFDM系统的影响分析

针对相干光正交频分复用系统中出现的高峰值平均功率比问题,提出分数阶傅里叶变换与高峰值平均功率比抑制算法相结合的方法.计算表明:随着分数阶傅里叶变换阶数的减小,信号的峰值平均功率比逐渐降低;与抑制算法结合后可进一步降低系统的峰值平均功率比,并解决抑制算法影响系统性能的问题.从结合的兼容性、抑制高峰值平均功率比效果及改善引入抑制算法后对系统的负面影响三方面进行仿真分析,结果表明:采用选择性映射算法与分数阶傅里叶变换结合后,旋转因子同为4时,峰值平均功率比高于6.6dB的概率较单一选择性映射算法低104;选取高峰值平均功率比抑制情况相近时,结合算法的时间复杂度比单一选择性映射算法降低了8倍;采用限幅算法与分数阶傅里叶变换结合的仿真情况也较单一限幅算法有很大提高,表明该算法结合的兼容性良好.     

A Diode-Pumped 1617 nm Single Longitudinal Mode Er：YAG Laser with Intra-Cavity Etalons

We demonstrate the continuous wave p-polarized single longitudinal mode （SLM） operation of an Er：YAG laser at 1617.6nm pumped by a diode-laser with three inserted Fabry-Perot （FP） etalons at room temperature. The Brewster angle inserted FP is applied to obtain the p-polarized laser. For free running, the maximum output power is 570 m W with a pump power of 12.5 W. An incident pump power of 12.5 W is used to generate the maximum p-polarized single longitudinal mode output power of 78.5 m W, corresponding to a slope efficiency of 1.6% and an optical-to-optical efficiency of 0.61%. The beam quality M2 is measured to be 1.15 at the highest SLM output power. This stable polarized SLM oscillation is encouraging due to its application for an injection-locked system used as a master laser.     

ICRH带状双天线的间距对等离子体耦合特性的影响

采用能量一次吸收假设、等离子体平板模型和三维天线模型数值模拟离子回旋共振加热时带状双天线与等离子体的耦合过程,得到天线的辐射功率、等离子体的吸收功率密度分布随天线间距变化的关系.通过对比分析,得出结论:在一定实验条件下,当带状双天线同相馈电时,天线间距越小,离子回旋共振加热效果越好.     

Experimental investigation on a software synchronous optical sampling technique based on periodically poled lithium niobate

A software synchronous optical sampling system is constructed based on sum frequency generation (SFG) in periodically poled lithium niobate (PPLN). Five gigahertz of a non-return-to-zero (NRZ) data signal is sampled by sampling pulse with the repetition frequency of 29.31 MHz. The power of the SFG light is set at 23 dBm, and an eye diagram is successfully recovered. A band-pass filter is added before the sampling pulse is subjected to erbium-doped fiber amplifier to reduce gain competition and ensure a high power level of SFG.     

微波场中Josephson结的微波发射与吸收研究

采用数值仿真方法,研究微波场中约瑟夫森结微波感应台阶处的功率特性。发现微波场中约瑟夫森结不止吸收辐射,也发射辐射的情况。得到微波辐照和结电阻对功率吸收和发射的影响规律。结果表明,处于发射功率的状态对应的偏置电流范围占整个台阶总电流范围的比例可以趋于50%。这一发现对约瑟夫森结理论和应用研究具有重要的意义。     

Error and jitter e ect studies on the SLED for the BEPCⅡ-linac

An RF pulse compressor is a device used to convert a long RF pulse to a short one with a much higher peak RF magnitude. SLED can be regarded as the earliest RF pulse compressor to be used in large-scale linear accelerators. It has been widely studied around the world and applied in the BEPC and BEPCⅡ linac for many years. During routine operation, error and jitter effects will deteriorate the performance of SLED, either on the output electromagnetic wave amplitude or phase. The error effects mainly include the frequency drift induced by cooling water temperature variation and the frequency/Q₀/β unbalances between the two energy storage cavities caused by mechanical fabrication or microwave tuning. The jitter effects refer to the PSK switching phase and time jitters. In this paper, we re-derive the generalized formulae for the conventional SLED used in the BEPCⅡ linac, and the error and jitter effects on SLED performance are also investigated.     

Airy光束在Kerr介质中的传输特性

通过对非线性薛定谔方程的研究,得出Airy光束在Kerr介质中的崩塌功率及有效束宽演化的解析表达式。经过数值计算发现,Airy光束在聚焦的Kerr介质中,其主瓣在开始传播时始终是会聚的;当输入功率小于临界崩塌功率时,Airy光束主瓣的中心部分出现局部崩塌。在不同的Kerr介质中, Airy光束的形状和传输轨道均能保持不变,如同在自由空间中传播,但光场大小的分布,随着不同的Kerr介质会发生改变:在Kerr的聚焦介质中,光场向中心聚焦;而在散焦的Kerr介质中,光场会发散。     

红外光谱法研究射频功率对微晶硅薄膜微结构的影响

采用射频等离子体增强化学气相沉积(RF-PECVD)技术,在硅衬底上以不同的射频功率生长微晶硅(μc-Si:H)薄膜,利用傅里叶变换红外透射光谱技术对薄膜进行测试.通过对红外透射光谱的高斯拟合分析,结果表明薄膜中的氢含量和硅氢键合模式跟射频功率密切相关;当射频率从30W增加到110W时,薄膜中的氢含量先减少后慢慢增加,而结构因子逐渐增加后再减小,并且硅氢键合模式由以SiH为主转变为以SiH2为主.并讨论了这些参量随射频功率变化的机理.     

耦合带状线定向耦合器大功率合成器的设计

介绍了直线加速器高频全固态功率源中大功率合成器件-3 dB定向耦合器的理论计算和工程设计过程, 该合成器工作频率80.5 MHz, 输出连续波功率大于20 kW。 分析了合成器的功率容量, 并对相应的理论计算结果、 CST (Computer Simulation Technology)软件模拟计算结果和实际功率合成器件测量结果进行了比较。 通过比较得出, CST仿真结果与测试结果基本一致, 隔离度和电压驻波比等实测指标优于设计指标, 只有耦合度与设计指标有些偏差, 总体上达到了预期的设计要求。 在输出功率20 kW时, 取样波形无失真, 合成器无明显温升, 满足固态功率源大功率稳定运行的要求。 The principle of design and calculation of the power synthesis in the solid state amplifier are described in this paper. The working frequency of the synthesizer is 80.5 MHz. The output continuous wave power is more than 20 kW; The synthesizer power capacity is analyzed. The theoretical calculation results, Computer Simulation Technology (CST) simulated results are compared with the measured results of the actual 3 dB couplers. The analysis of the measured results and CST calculated results shows that the simulation is in agreement with the measurement results which meet the design requirements of the solid state amplifier. Except the coupling coefficient, the isolation, the VSWR and other parameters are better than the design target. When the output power is 20 kW, the sampling waveform has no deform and the temperature of the synthesizer is stable.