Anodizing of high electrically stressed components

Abstract

Anodizing creates an aluminum oxide coating that penetrates into the surface as well as builds above the surface of aluminum creating a very hard ceramic-type coating with good dielectric properties. Over time and use, the electrical carrying components (or spools in this case) experience electrical breakdown, yielding undesirable x-ray dosages or failure. The spool is located in the high vacuum region of a rod pinch diode section of an x-ray producing machine. Machine operators have recorded decreases in x-ray dosages over numerous shots using the reusable spool component, and re-anodizing the interior surface of the spool does not provide the expected improvement. A machine operation subject matter expert coated the anodized surface with diffusion pump oil to eliminate electrical breakdown as a temporary fix. It is known that an anodized surface is very porous, and it is because of this porosity that the surface may trap air that becomes a catalyst for electrical breakdown. In this paper we present a solution of mitigating electrical breakdown by oiling. We will also present results of surface anodizing improvements achieved by surface finish preparation and surface sealing. We conclude that oiling the anodized surface and using anodized hot dip sealing processes will have similar results.

Modeling power flow in the induction cavity with a two dimensional circuit simulation

“…This value should not exceed the explosive electron emission threshold. A better design usually keeps the maximum electric field less than 200 kV=cm on any negative cathode plate surface, and the hard anodize technique is frequently employed on this part to enhance the explosive electron emission threshold [35]. Figure 8 displays the output transmission line voltage waveforms acquired by 1D, 2D circuit simulations, and transient electromagnetic simulation.…”

Design of a 1-MV induction cavity and validation of the two-dimensional circuit model

“…Anodizing is a process of creating a very hard ceramictype coating on the aluminum and its alloy surface. The thickness of the film formed by the hard anodizing process is higher than 25.0 μm [29,30]. The electric field on the electrode surface will be reduced by a factor of ε r by this dielectric layer, where ε r is the relative permittivity of the coating film.…”