With the development of industrial civilization, advanced manufacturing technology has attracted widespread concern, including in the aerospace industry. In this paper, we report the applications of ultra-thin atomic layer deposition nanofilm in the advanced aerospace manufacturing industry, including aluminum anti-oxidation and secondary electron suppression, which are critical in high-power and miniaturization development. The compact and uniform aluminum oxide film, which is formed by thermal atomic layer deposition (ALD), can prevent the deep surface oxidation of aluminum during storage, avoiding the waste of material and energy in repetitive production. The total secondary electron yield of the C/TiN component nanofilm, deposited through plasma-enhanced atomic layer deposition, decreases 25% compared with an uncoated surface. The suppression of secondary electron emission is of great importance in solving the multipactor for high-power microwave components in space. Moreover, the controllable, ultra-thin uniform composite nanofilm can be deposited directly on the complex surface of devices without any transfer process, which is critical for many different applications. The ALD nanofilm shows potential for promoting system performance and resource consumption in the advanced aerospace manufacturing industry.

Charging effects of dielectric due to space electron beam irradiation have a huge impact on spacecraft. To understand charging equilibrium characteristics of dielectric under electron beam irradiation, in this paper, we present a novel numerical simulation method for analyzing the secondary electron yield (SEY) based on a charging balance mode. We used the Mott scattering model and the Penn dielectric function (PDF) model to calculate the collisions between incident electrons and material the atoms of material. For internal charge transport, we considered the processes of drift, diffusion, trapping, and neutralization. These were calculated with a finite-difference time-domain (FDTD) method. Based on mechanisms of import-export dynamic charge evolution, charging balance can be categorized into three modes: SE mode, leakage (LE) mode, and cooperation (CO) mode (a combination of the two). In most situations, the SE mode corresponds to the surface charging state, while the LE mode always corresponds to deep charging states. Shortening the distance of free charge transport, a thinner sample is more likely to present as LE mode. Although the surface potential can be enhanced by monotonously increasing the thickness, the total internal charge quantity approaches a local maximum with thickness because of a charging balance mode transformation. In addition, with a larger average density of carriers in the LE mode, the material conductivity is enhanced and the dielectric loss tends to be larger at low frequencies (<10³ Hz). The charging balance mode method in this study can also be appropriate to the analyses of altering irradiation parameters and materials intrinsic parameters.

It is known that an appropriate surface structure can suppress the secondary electron emission as a result of the receded multipactor in a spacecraft microwave component. On the other hand, the multiplier effect caused by electron re-entrance in ordinary surface structures can degrade the suppression of secondary electron emission. The present paper concerns our proposition of a new type of two-level nested microtrap structure surface able to effectively inhibit the generation of the secondary electrons inside the trap structure to achieve better suppression of the total secondary electron emission on the surface. The surface of a two-level nested microtrap array structure was obtained by lithography, stripping, dry etching, and Ag sputtering. Experimental tests were conducted on the two proposed nested structures with different sizes. The test results show that inhibition effects of the two structures have been improved by 100% and 144% compared with those of the traditional single-hole trap structure. The secondary electron yield on the bottom surface of the rough nested trap due to Ag sputtering is higher than that of the ideal regular structure simulated by Monte Carlo. In addition, the larger depth-to-width ratio of the nested trap can inhibit the multi-generation multiplication of electrons in the trap more effectively and further improve the inhibition effect on secondary electrons. For an impedance transformer, the proposed two size nested structure surface can increase the multipactor power threshold by about 346% and 386%. This method plus the nested microtrap structure can achieve a better secondary electron emission suppression effect and further improve the multipactor threshold of space microwave components.

High-power microwave-induced low-pressure discharges seriously threaten the reliability of space payload systems. Under extremely low-pressure conditions, the evolution of ionized and secondary electrons at the initial stage of discharge is crucial to figure out the discharge process. Therefore, this paper investigates the development of multiple electrons in the discharge process under a highly low-pressure environment using numerical simulation. A three-dimensional simulation model based on the Monte Carlo algorithm is established by considering various electron-gas collisions and secondary electron emissions from different material surfaces. The evolution characteristics of various electrons' populations, energy, and distribution patterns during the discharge process are analyzed. In addition, the influence of the critical conditions at different air pressures on the electron evolution during the discharge process and the intrinsic causes are also investigated. This study is significant in revealing the transition characteristics between multipactor and low-pressure discharge and exploring their inherent mechanisms.

An analytical model is developed to calculate the secondary electron yield (SEY) of composite layered structures, based on two independent physical parameters of secondary electron emission. For the same material, different processing techniques can result in significant variations in material surface conditions and microstructures, resulting in discrepancies in the excitation and escape capabilities of secondary electrons. The present model integrates the secondary electron excitation mechanism with Bethe’s stopping power expression, which can calculate the average mean free path and excitation energy threshold of thin dielectric films, providing a quantitative evaluation of contributions from each layer. Good agreement is observed between model predictions and experimental results for nanometer-scale ALD-Al2O3 films on Ag substrates. The results show that SEY is strongly dependent on the film thickness. The SEY curve of the film in the composite structure resembles that of a bulk material, but with a lower peak due to the limited thickness. As the film thickness increases, a larger contribution from the top layer and a further reduced contribution from the substrate are observed. This model offers a theoretical method for SEY evaluation in layered structures and can support the film thickness design in multipactor suppression and dynode films in electron detectors.