TiN coated aluminum electrodes for DC high voltage electron guns

Abstract

Preparing electrodes made of metals like stainless steel, for use inside DC high voltage electron guns, is a labor-intensive and time-consuming process. In this paper, the authors report the exceptional high voltage performance of aluminum electrodes coated with hard titanium nitride (TiN). The aluminum electrodes were comparatively easy to manufacture and required only hours of mechanical polishing using silicon carbide paper, prior to coating with TiN by a commercial vendor. The high voltage performance of three TiN-coated aluminum electrodes, before and after gas conditioning with helium, was compared to that of bare aluminum electrodes, and electrodes manufactured from titanium alloy (Ti-6Al-4V). Following gas conditioning, each TiN-coated aluminum electrode reached À225 kV bias voltage while generating less than 100 pA of field emission (<10 pA) using a 40 mm cathode/anode gap, corresponding to field strength of 13.7 MV/m. Smaller gaps were studied to evaluate electrode performance at higher field strength with the best performing TiN-coated aluminum electrode reaching $22.5 MV/m with field emission less than 100 pA. These results were comparable to those obtained from our best-performing electrodes manufactured from stainless steel, titanium alloy and niobium, as reported in references cited below. The TiN coating provided a very smooth surface and with mechanical properties of the coating (hardness and modulus) superior to those of stainless steel, titanium-alloy, and niobium electrodes. These features likely contributed to the improved high voltage performance of the TiN-coated aluminum electrodes. V

Electric dipole moments and the search for new physics

“…E = 4.4 MV/m is conservative. A "green field" pEDM experiment could have up to E = 5 MV/m without R&D progress, see [383][384][385]. Tests with beams and polarimeters at several laboratories (BNL, KVI, COSY) have consistently demonstrated over more than a decade that the requirements of storage ring EDM search are within reach [387][388][389][390][391][392][393][394].…”

Thin film studies toward improving the performance of accelerator electron sources

“…For vent-no bake vacuum protocol, the pressure was ~10 Electron accelerators generate highly energetic electron beams that are utilized for a variety of basic research and industrial applications [1][2][3]. The diverse application of electron-beams includes investigation of the fundamental nature of matter, characterization and modification of material properties, surface treatment and semiconductor processing, microscopic surface physics studies, radiation therapy for medical sterilization, inspection of nuclear fuels, production of fissile materials for nuclear weapon, and many more [4,5].…”

“…An electron gun operates under very high vacuum where a cathode produces the free electron beam delivered to the accelerator that increases the energy of the electron. Electron beam technology has undergone numerous modifications over the long history of the development of electron beam devices [2].…”

“…This dissertation is based on the published work in journals [43][44][45][46]. Chapter 2 presents the study measuring the outgassing rates of three nominally identical 304L stainless steel vacuum chambers to determine the effects of chamber coatings (amorphous silicon and titanium nitride) and heat treatments on reducing the gas load to achieve better vacuum.…”

“…After being cut to shape with hydrocarbon-free lubricants, each electrode was polished on a potter's wheel with silicon carbide paper of increasingly finer grit: 400, 600, and 800 particles/in. 2 . Two electrodes were further polished using 1200 particles/in.…”