scholarly journals Near-field shock formation in noise propagation from a high-power jet aircraft

2013 ◽  
Vol 133 (2) ◽  
pp. EL88-EL93 ◽  
Author(s):  
Kent L. Gee ◽  
Tracianne B. Neilsen ◽  
J. Micah Downing ◽  
Michael M. James ◽  
Richard L. McKinley ◽  
...  
Keyword(s):  
High Power ◽  
Near Field ◽  
Shock Formation ◽  
Noise Propagation

scholarly journals Near-field thermophotovoltaics for efficient heat to electricity conversion at high power density

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Rohith Mittapally ◽  
Byungjun Lee ◽  
Linxiao Zhu ◽  
Amin Reihani ◽  
Ju Won Lim ◽  
...  
Keyword(s):  
Power Density ◽  
High Power ◽  
High Efficiency ◽  
Near Field ◽  
Electrical Power ◽  
Photovoltaic Cells ◽  
High Power Density ◽  
Pv Cell ◽  
Electrical Power Output ◽  
Power Densities

AbstractThermophotovoltaic approaches that take advantage of near-field evanescent modes are being actively explored due to their potential for high-power density and high-efficiency energy conversion. However, progress towards functional near-field thermophotovoltaic devices has been limited by challenges in creating thermally robust planar emitters and photovoltaic cells designed for near-field thermal radiation. Here, we demonstrate record power densities of ~5 kW/m2 at an efficiency of 6.8%, where the efficiency of the system is defined as the ratio of the electrical power output of the PV cell to the radiative heat transfer from the emitter to the PV cell. This was accomplished by developing novel emitter devices that can sustain temperatures as high as 1270 K and positioning them into the near-field (<100 nm) of custom-fabricated InGaAs-based thin film photovoltaic cells. In addition to demonstrating efficient heat-to-electricity conversion at high power density, we report the performance of thermophotovoltaic devices across a range of emitter temperatures (~800 K–1270 K) and gap sizes (70 nm–7 µm). The methods and insights achieved in this work represent a critical step towards understanding the fundamental principles of harvesting thermal energy in the near-field.

Near field analysis of CSG and BSG combined element under high power laser condition

2006 ◽  
Author(s):  
Xin Yao ◽  
Fuhua Gao ◽  
Yixiao Zhang ◽  
Lei Wang ◽  
Yongkang Guo ◽  
...  
Keyword(s):  
High Power ◽  
Near Field ◽  
Field Analysis ◽  
High Power Laser ◽  
Power Laser ◽  
Laser Condition

Identifying Defects in Thin Film of High Power Laser Lens by Using Near Field Microimaging Method

2017 ◽  
Vol 44 (1) ◽  
pp. 0103001
Author(s):  
白忠臣 Bai Zhongchen ◽  
黄兆岭 Huang Zhaoling ◽  
郝礼才 Hao Licai ◽  
陆安江 Lu Anjiang ◽  
秦水介 Qin Shuijie
Keyword(s):  
Thin Film ◽  
High Power ◽  
Near Field ◽  
High Power Laser ◽  
Power Laser

Improving near field of high-power laser beams

2011 ◽  
Vol 23 (4) ◽  
pp. 959-962
Author(s):  
谢娜 Xie Na ◽  
黄晚晴 Huang Wanqing ◽  
郭仪 Guo Yi ◽  
王晓东 Wang Xiaodong ◽  
方香云 Fang Xiangyun ◽  
...  
Keyword(s):  
High Power ◽  
Near Field ◽  
Laser Beams ◽  
High Power Laser ◽  
Power Laser

Cylindrical Fourier near‐field acoustical holography applied to a high‐power jet.

2011 ◽  
Vol 129 (4) ◽  
pp. 2493-2493
Author(s):  
David W. Krueger ◽  
Kent L. Gee ◽  
Alan T. Wall ◽  
Scott D. Sommerfeldt ◽  
Jonathan D. Blotter
Keyword(s):  
High Power ◽  
Near Field ◽  
Acoustical Holography

scholarly journals High Power THz Generation from Sub-ps Bunches of Relativistic Electrons

2004 ◽  
Vol 850 ◽  
Author(s):  
S. Benson ◽  
D. R. Douglas ◽  
H. F. Dylla ◽  
J. Gubeli ◽  
K. Jordan ◽  
...  
Keyword(s):  
High Power ◽  
Near Field ◽  
Fourth Power ◽  
Thz Spectroscopy ◽  
Relativistic Electrons ◽  
Time Resolved ◽  
Picosecond Pulses ◽  
Coulomb Term ◽  
Joseph Larmor ◽  
New Generation

ABSTRACTWe describe a > 100 Watt broadband THz source that takes advantage of the relativistic enhancement of the radiation from accelerating electrons according to the formula assigned the name of Sir Joseph Larmor[1, 2]. This is in contrast to the typical 1 milliwatt sources available in a laboratory. Specifically, for relativistic electrons the emission is enhanced by the fourth power of the increase in mass. Thus for 100 MeV electrons, for which the mass increases by a factor of ∼ 200, the enhancement is > 109. The experiments use a new generation of light source called an energy recovery linac (ERL) [3], in which bunches of electrons circulate once, but in which their energy is recovered. In such a machine the electron bunches can be very much shorter than those, say, in storage rings or synchrotrons.The Jefferson Lab facility operates in new limits of emission from relativistic particles involving both multiparticle coherence and near-field emission in which the velocity (Coulomb) term in the classical electrodynamical theory becomes as important as the acceleration term (synchrotron radiation).The sub-picosecond pulses of light offer unique capabilities in 2 specific areas, namely time-resolved dynamics, and imaging. High resolution THz spectroscopy has recently revealed sharp vibrational modes for many materials including malignant tissue, proteins, DNA, pharmaceuticals and explosive materials. Energetically the THz range embraces superconducting bandgaps, and regions of intense interest in the understanding of systems in which correlated motions of electrons are important, such as colossal magneto-resistive and high-Tc materials. The very high power levels of the new source will allow non-linear effects to be observed as well as the creation of novel states of materials, including electric-field driven localization[4]. We will give examples of existing work in these areas and present opportunities afforded by the new source.

Die Bonding of High Power 808 nm Laser Diodes With Nanosilver Paste

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
Yi Yan ◽  
Xu Chen ◽  
Xingsheng Liu ◽  
Yunhui Mei ◽  
Guo-Quan Lu
Keyword(s):  
Semiconductor Laser ◽  
High Power ◽  
Near Field ◽  
Laser Diodes ◽  
Acoustic Microscopy ◽  
High Power Laser ◽  
Power Laser ◽  
Power Semiconductor ◽  
Die Bonding ◽  
Nanosilver Paste

Conduction-cooled high power laser diodes have a variety of significant commercial, industrial, and military applications. For these devices to perform effectively, an appropriate die-attached material meeting specific requirements must be selected. In this study, nanosilver paste, a novel die-attached material, was used in packaging the 60 W 808 nm high power laser diodes. The properties of the laser diodes operating in the continuous wave (CW) mode, including the characteristics of power–current–voltage (LIV), spectrum, near field, far field, near field linearity, spatial spectrum, and thermal impedance, were determined. In addition, destructive tests, including the die shear test, scanning acoustic microscopy, and the thermal rollover test, were conducted to evaluate the reliability of the die bonding of the 60 W 808 nm high power semiconductor laser with nanosilver paste. Thermal analyses of the laser diodes operating at CW mode with different die-attached materials, indium solder, gold–tin solder and nanosilver paste, were conducted by finite element analysis (FEA). According to the result of the FEA, the nanosilver paste resulted in the lowest temperature in the laser diodes. The test results showed that the nanosilver paste was a very promising die-attached material in packaging high power semiconductor laser.

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