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The pulsed plasma thruster (PPT) is one sort of promising electric thrusters, but the low efficiency is always a big problem for PPT. Many researches have been working on solving this problem. However, there is still no significant breakthrough. This paper aimed to discuss some methods for improving the PPT's efficiency.

The causes for the low efficiency by analyzing the theoretical models of PPT are discussed, and the influences on PPT's performance investigated in terms of the structural or electrical parameters.

The change of structural or electrical parameters which influence the thrust efficiency significantly are taken into account. In the process of designing PPT, optimized structural and electrical parameters should be chosen to attain a better performance.

This analysis is mainly based on the parallel‐rail PPT.

The result of analysis is adopted, the higher thrust efficiency of PPT is expectable.

By introducing theoretical models and analyzing results of some researcher's experiments, this paper offers a method of designing PPT and attempts to help designer to choose appropriate structural and electrical parameters.

The purpose of this paper is to propose and assess the possibility of using ceramic coating layer as a heat‐resistant material in micro solid propellant thruster.

A ceramic layer is coated on the inner surface of the combustor of a micro thruster by applying micro‐arc oxidation (MAO) technology. The thermal property of the coating is analyzed with laser pulse method. To evaluate the heat‐resistant performance of the coating, the temperature history of the micro thruster inner surface is experimentally tested and recorded in a water thermostat bath. A numerical simulation of the thruster working condition is also carried out.

Both experimental and simulation results reveal that the heat‐resistant ability of the coating processed by MAO is proven to be effective.

This paper attempts to help designers choose material processing technology to improve micro solid propellant thruster heat‐resistant ability.

The paper shows that with a ceramic coating layer processed with MAO, aluminium can sustain higher temperature and it can be used as the structural material for short‐time‐work micro thruster.

Field emission electric propulsion (FEEP) thruster is a type of electric propulsion based on space‐proven indium liquid metal ion sources. The lifetime of FEEP thruster limits its application in space. A better method to improve its lifetime is the reduction of emission current. This paper aims to discuss the minimum emission current of operating FEEP thrusters.

In this work, theoretical models, including fluid‐flow model and ion formation model, are analyzed. Current densities of these models are discussed and the minimum emission current is calculated.

There are few equilibrium states under low emission current conditions. However, the minimum emission current is the only stable state at which the FEEP thruster can operate.

This analysis is mainly based on the needle indium FEEP, which is compared indirectly with experiments of gallium.

This paper attempts to help designers choose appropriate electric parameters to improve the lifetime of FEEP.

By introducing and analyzing theoretical models, this paper calculates the minimum emission current for stable operation of FEEP.

Without proper treatment, waste cooking oil (WCO) will bring serious environmental and health hazards, which can be effectively alleviated by converting it into biofuel. Subsidies from the government usually play a significant role in encouraging recycling activities and supporting sustainable supply chain. This paper aims to quantitatively investigate the incentive effects of government subsidies under asymmetric information.

This paper applies the principal–agent contract to compare the incentive effects of the two widely used subsidy modes (raw material price subsidy [MS] and finished product sale subsidy [FS]) in a management system which consists of the government and a bio-firm where the bio-firm’s conversion rate of the WCO remains as private information.

Results indicate that the two subsidy modes have the same performance under symmetric information, while under asymmetric information, the government always prefers the MS mode which is more environment-friendly. Besides, if the average conversion rate is large or the uncertainty level of the asymmetric information is moderate, the MS mode is Pareto-improving compared with the FS mode for the government and the high-type bio-firm. Only when the average conversion rate is small or the uncertainty level is very small/very large, the high-type bio-firm welcomes the FS mode.

Different from the existing literature, this paper applies the principal–agent contract into the WCO management system and quantitatively compares the two subsidy modes taking the practical problem of asymmetric information into consideration.

The purpose of this paper is to study the effect of ultrasonic machining process parameters on surface quality while machining titanium alloy Ti-6Al-4V.

Effect of cryogenic treatment (CT) of tool and work material was also explored in the study. Taguchi’s L18 orthogonal array was chosen for design of experiments and average surface roughness was measured.

Different modes of fracture were detected at work surface corresponding to varied input process parameters. Slurry grit size, power rating and tool material along with CT of work material were found to be the significant parameters affecting surface quality.

The results obtained have been modelled using artificial neural network approach.