Sputtering yield measurements during low energy xenon plasma bombardment

Abstract

The sputtering yields of molybdenum, titanium, beryllium, and carbon have been measured during xenon ion bombardment from a plasma in the energy range between 10 and 200 eV. The erosion rates of Mo, Be, and C are measured both spectroscopically in the plasma and using the standard weight loss technique. Spectroscopic measurements of Ti sputtering yields, where no atomic physics data is available, are normalized to the weight loss measurements. The erosion rates of the metals decrease with the reduced mass of the metal-xenon combination and decrease with the increasing metal's binding energy, as expected. The erosion results for bombardment of graphite indicate that the sputtering rate of carbon, as atoms, from the surface is insufficient to explain the total carbon weight loss measured. The multiple mechanisms for carbon erosion during plasma bombardment are discussed and the sputter rates of carbon atoms and carbon dimers are presented.

Interaction of beryllium containing plasma with ITER materials

“…The beryllium eroded from the sample surface can be observed by monitoring the neutral beryllium line emission (at 457.3 nm) from directly in front of the exposed target [13]. By examining, in detail, the temporal evolution of a typical beryllium seeded plasma exposure in PISCES-B, one can clearly see the increasing beryllium erosion from the sample surface.…”

Sputtering Yield of Carbon-Carbon Composite Due to Xenon Ion Bombardment in Ion Engines

“…This inconsistency can be avoided by assigning an upper limit to f=f s in Eq. (8). Figure 4 shows a comparison of sputtering yields for different upper limits of f=f s .…”

“…However, for carbon, it offers significantly low sputtering yield values in the lower incidence energy regions. This problem was solved by Kenmotsu et al 23) using the experimental fact that 14% of Xe is adsorbed in the surface of carbon, 8) which lowers the threshold energy of sputtering. The formula proposed by Kenmotsu is given as follows: combining two surface states (threshold energy of Trans.…”

“…Large amounts of experimental data are available for the normal incidences of graphite, diamond, and pyrographite, [8][9][10][11][12][13][14][15] that can be used to derive some empirical formula by curve-fitting, and this approach is widely used in engineering applications. In contrast, only small amounts of experimental data are available to derive an empirical formula for the angular dependence of sputtering.…”

Development of Real-time Erosion Monitoring System for Hall Thrusters by Cavity Ring-Down Spectroscopy

“…The need for a sensitive nonintrusive measurement suggests the use of optical techniques. Optical emission spectroscopy (OES) 17,18) , laser induced fluorescence (LIF) 19) and multi-photon ionization coupled to a time of flight mass spectrometer 20,21) have been used for species-specific sputtering measurements. The use of LIF has been particularly extensive and has proven to be very effective for velocity measurement though challenging for quantitative number density.…”