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Motivated by the possibility of guiding daughter ions from double beta decay events to single-ion sensors for barium tagging, the NEXT collaboration is developing a program of R&D to test radio frequency (RF) carpets for ion transport in high pressure xenon gas. This would require carpet functionality in regimes at higher pressures than have been previously reported, implying correspondingly larger electrode voltages than in existing systems. This mode of operation appears plausible for contemporary RF-carpet geometries due to the higher predicted breakdown strength of high pressure xenon relative to low pressure helium, the working medium in most existing RF carpet devices. In this paper we present the first measurements of the high voltage strength of xenon gas at high pressure and at the relevant RF frequencies for ion transport (in the 10 MHz range), as well as new DC and RF measurements of the breakdown strengths of high pressure argon and helium gases at small gap sizes. We find breakdown voltages that are compatible with stable RF carpet operation given the gas, pressure, voltage, materials and geometry of interest.

Dielectric breakdown strength is one of the critical performance metrics for pure gases and gas mixtures used in large, high pressure gas time projection chambers. In this paper we experimentally study dielectric breakdown strengths of several important time projection chamber working gases and gas-phase insulators over the pressure range 100 mbar to 10 bar, and gap sizes ranging from 0.1 to 10 mm. Gases characterized include argon, xenon, CO$$_2$$ 2 , CF$$_4$$ 4 , and mixtures 90-10 argon-CH$$_4$$ 4 , 90-10 argon-CO$$_2$$ 2 and 99-1 argon-CF$$_4$$ 4 . We develop a theoretical model for high voltage breakdown based on microphysical simulations that use electron swarm Monte Carlo results as input to Townsend- and Meek-like discharge criteria. This model is shown to be highly predictive at high pressure, out-performing traditional Paschen–Townsend and Meek–Raether models significantly. At lower pressure-times-distance, the Townsend-like model is an excellent description for noble gases whereas the Meek-like model provides a highly accurate prediction for insulating gases.

A 23-mm-i.d. torch is described and evaluated for use in inductively coupled plasma mass spectrometry. The plasma operates optimally at 1.50 kW forward power and 19.2 L/min total argon flow. The effect of the customary operating parameters (nebulizer flow rate, rf power, sampling depth, and ion-lens voltages) on analyte signals is discussed. Detection limits, oxide-ion ratios, and doubly charged ion ratios have been measured and are compared with those produced by an 18-mm-i.d. low-flow MAK torch. When compared to the conventional torch, the 23-mm system exhibits comparable detection limits for low-mass ions but better detection limits for high-mass ions (Pb and U). Oxide-ion ratios are lower in the larger torch, but doubly charged ion ratios are higher. Because optimal sampling depths in the larger torch are higher, entrained air in the tail flame causes instability and results in increased ArO+ and ArN+ background signals.

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