High power performance limits of fiber components

Author(s):  
Nigel Holehouse ◽  
Julien Magné ◽  
Mathieu Auger
2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Hideaki Hotchi

AbstractWith the spread of accelerator-driven pulsed spallation neutron sources and increasing need for higher neutron fluxes, the high-power performance of proton accelerators has greatly advanced from a few kilowatts to more than 1 MW in the last four decades. The most important concerns to realize such a high-power beam operation are controlling and minimizing beam loss, which are essential for sustainable beam operation that allows hands-on maintenance. This paper reviews key devices and beam handling techniques for beam loss control employed in the high-power proton accelerators that are currently in operation for pulsed spallation neutron sources, including their operational status and future upgrade plan.


2001 ◽  
Vol 22 (11) ◽  
pp. 504-506 ◽  
Author(s):  
V. Tilak ◽  
B. Green ◽  
V. Kaper ◽  
H. Kim ◽  
T. Prunty ◽  
...  

2011 ◽  
Vol 2011 (HITEN) ◽  
pp. 000027-000029
Author(s):  
K. Bridger ◽  
A. Cooke ◽  
D. Kohlhafer ◽  
R. Strite ◽  
W. Schulze ◽  
...  

Power conversion electronics in military vehicles and aircraft are currently experiencing high temperatures and future generations will see these temperatures rise even higher. The high temperatures arise not only from the environment but also from high power dissipation in the components themselves. Capacitors can occupy almost 50% of the real estate in some power converters and these capacitors are subjected to very high currents at high frequencies in dc-dc converters or 60-Hz 120 VAC in the output stage of an inverter. Dissipation resulting from the high power levels can lead to internal capacitor temperatures at least 50°C above their ambient and so for military hybrid electric vehicles (HEVs) capacitors are expected to reach at least 150°C and possibly 200°C, while future aircraft component temperatures are expected to exceed 250°C. A new family of high-temperature dielectrics based on sodium bismuth titanate has been developed by these authors and capacitors are now available from Novacap under the trade name “Type H” or “Type HA”. This paper examines the high-frequency, high-current and 60-Hz, 120-VAC performance of these capacitors including an estimate of internal heating. The primary operating temperature range studied is −40 to +150°C, although some higher temperature data are also presented.


2020 ◽  
Vol 60 (4) ◽  
pp. 852-863
Author(s):  
Stephen M Deban ◽  
Roi Holzman ◽  
Ulrike K Müller

Abstract Suction feeding has evolved independently in two highly disparate animal and plant systems, aquatic vertebrates and carnivorous bladderworts. We review the suction performance of animal and plant suction feeders to explore biomechanical performance limits for aquatic feeders based on morphology and kinematics, in the context of current knowledge of suction feeding. While vertebrates have the greatest diversity and size range of suction feeders, bladderworts are the smallest and fastest known suction feeders. Body size has profound effects on aquatic organismal function, including suction feeding, particularly in the intermediate flow regime that tiny organisms can experience. A minority of tiny organisms suction feed, consistent with model predictions that generating effective suction flow is less energetically efficient and also requires more flow-rate specific power at small size. Although the speed of suction flows generally increases with body and gape size, some specialized tiny plant and animal predators generate suction flows greater than those of suction feeders 100 times larger. Bladderworts generate rapid flow via high-energy and high-power elastic recoil and suction feed for nutrients (relying on photosynthesis for energy). Small animals may be limited by available muscle energy and power, although mouth protrusion can offset the performance cost of not generating high suction pressure. We hypothesize that both the high energetic costs and high power requirements of generating rapid suction flow shape the biomechanics of small suction feeders, and that plants and animals have arrived at different solutions due in part to their different energy budgets.


Circuit World ◽  
2020 ◽  
Vol 46 (4) ◽  
pp. 243-248
Author(s):  
Min Liu ◽  
Panpan Xu ◽  
Jincan Zhang ◽  
Bo Liu ◽  
Liwen Zhang

Purpose Power amplifiers (PAs) play an important role in wireless communications because they dominate system performance. High-linearity broadband PAs are of great value for potential use in multi-band system implementation. The purpose of this paper is to present a cascode power amplifier architecture to achieve high power and high efficiency requirements for 4.2∼5.4 GHz applications. Design/methodology/approach A common emitter (CE) configuration with a stacked common base configuration of heterojunction bipolar transistor (HBT) is used to achieve high power. T-type matching network is used as input matching network. To increase the bandwidth, the output matching networks are implemented using the two L-networks. Findings By using the proposed method, the stacked PA demonstrates a maximum saturated output power of 26.2 dBm, a compact chip size of 1.17 × 0.59 mm2 and a maximum power-added efficiency of 46.3 per cent. The PA shows a wideband small signal gain with less than 3 dB variation over working frequency. The saturated output power of the proposed PA is higher than 25 dBm between 4.2 and 5.4 GHz. Originality/value The technology adopted for the design of the 4.2-to-5.4 GHz stacked PA is the 2-µm gallium arsenide HBT process. Based on the proposed method, a better power performance of 3 dB improvement can be achieved as compared with the conventional CE or common-source amplifier because of high output stacking impedance.


2000 ◽  
Vol 91 (1) ◽  
pp. 68-76 ◽  
Author(s):  
Peter J. Mahon ◽  
George L. Paul ◽  
Sarkis M. Keshishian ◽  
Anthony M. Vassallo

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