Conventional Efficiency Research Articles

The influence of energy recovery on the overall efficiency of acoustic sources at low frequencies

This paper defines a criterion called the overall efficiency (OE) for evaluating the efficiency of acoustic sources. In practice, the conventional efficiency (CE), is not capable of giving a comprehensive overview of the power consumption, especially in the connected amplifier drivers. The reason for this is that the CE is defined based on the nominal input electrical power. The nominal input electrical power is defined as the real part of the power that is delivered by the electrical amplifier to the actuation unit of an acoustic source. Therefore, power loss in the amplifier unit is not included in the CE definition. With the aid of the OE criterion, the effect of power loss in the connected amplifier units is taken into account. In particular, the application of the OE is crucial for acoustic sources that operate in a low frequency range. This is due to the reactive nature of power in both actuators and connected amplifiers. In the current paper, various combinations of amplifiers and actuators are studied. In particular, voice coil actuators and piezoelectric stack elements including both Lead Zirconate Titanate (PZT) ceramics and single crystal Lead Zirconate Niobate-Lead Titanate (PZN-PT) piezoelectric materials are investigated. In addition, the effect of a connected power driver is investigated. A class AB and a class D amplifier are studied respectively as analogue and switching amplifiers. Unlike a class AB amplifier, a class D amplifier is capable of energy recovery. A perforated flat acoustic source is examined in this paper as a practical example to verify the OE criterion. The numerical simulation on a thin acoustic source shows that for a single actuator, thanks to energy recovery, the OE is higher in a class D amplifier than that in a class AB amplifier. This study reveals that if a class D amplifier is the driver, using piezoelectric actuators results in a higher OE compared to using a voice coil actuator. Measurements on the sample acoustic source verify the numerical results presented in the current study.

Characterization of Solid Tin Target for Gas Discharges Produced EUV Plasmas

In the development of our Z-pinch plasma EUV source, xenon (Xe) is used for the background gas discharges, and a solid tin (Sn) rod is used as target material due to its potential of high convention efficiency (CE) from input electric energy to EUV radiation [1, 2]. The Z-pinch plasma was driven by pulsed current with amplitude of 30 kA and pulse duration of 110 ns. Pinhole imaging, EUV spectrograph and in-band EUV energy monitor were used to characterize the EUV emission from the Z-pinch discharge. The experimental analyses have demonstrated the CE was as high as 3% [3].