Buffer gas

About: Buffer gas is a research topic. Over the lifetime, 3565 publications have been published within this topic receiving 47283 citations.

Gas filling system and gas filling apparatus

Abstract: A gas filling apparatus (2) in the gas filling system (1) includes a precooler (18) for cooling hydrogen gas supplied from the gas supply source (11) and discharges the hydrogen gas cooled by the precooler (18) to fill the hydrogen gas into the gas tank (30). The temperature of the hydrogen gas cooled by the precooler (18) is detected by a gas temperature sensor (T) that detects, upstream of the gas tank (30), a temperature of the hydrogen gas cooled by the precooler (18). A flow rate controller (16) controls a filling flow rate of the hydrogen gas to be filled into the gas tank (30), based on the detected. temperature of the hydrogen gas. For example, when the detected temperature of the hydrogen gas is high, the filling flow rate' is reduced as compared to that when the detected temperature of the hydrogen gas is lower.

Compact Microwave Mercury Ion Clock for Deep-Space Applications

Abstract: We have recently completed a breadboard ion-clock physics package based on Hg ions shuttled between a quadrupole and a 16-pole rf trap. With this architecture we have demonstrated short-term stability ~1-2times10-13 at 1 second, averaging to 10-15 at 1 day. This development shows that H-maser quality stabilities can be produced in a small clock package, comparable in size to an ultra-stable quartz oscillator required for holding 1-2times10-13 second. This performance was obtained in a sealed vacuum configuration where only a getter pump was used to maintain vacuum. The vacuum tube containing the traps has now been under sealed vacuum conditions for nearly two years with no measurable degradation of ion trapping lifetimes or clock short-term performance. We have fabricated the vacuum tube, ion trap and UV windows from materials that will allow a ~400degC tube bake-out to prepare for tube seal-off. This approach to the vacuum follows the methods used in flight vacuum tube electronics, such as flight TWTA's where tube operation lifetime and shelf life of up to 15 years is achieved. We use neon as a buffer gas with 2-3 times less pressure induced frequency pulling than helium and, being heavier, negligible diffusion losses will occur over the operation lifetime.

Optimization of the Atomic Candle Signal for the Precise Measurement of Microwave Power

Abstract: To use the atomic candle signals of Cs atoms for the measurement of microwave power, the main parameters such as a standing or running microwave in the glass cell containing Cs atoms, the probing position in the waveguide, the intensity of the probing laser, the pressure of the $\hbox{N}_{2}$ buffer gas, and the beam diameter were optimized. As a result, the average uncertainty in obtaining the Rabi frequency, whose accuracy is important for the measurement of microwave power, was reduced several-fold. We demonstrated the measurement of microwave power using the optimized atomic candle signal in our previous work. In this paper, we discuss the optimization process in detail and the utility of optimizing the atomic candle signal for the precise measurement of microwave power.

High pressure mass spectrometry of volatile organic compounds with ambient air buffer gas

Abstract: Rationale There are many chemical measurement scenarios that would benefit from hand portable mass spectrometry tools including forensics, environmental monitoring, and safety and security. High pressure mass spectrometry (HPMS) facilitates miniaturization by significantly reducing vacuum system requirements. Previous work demonstrated HPMS using helium buffer gas, but HPMS conducted using ambient air would further reduce the size and weight of a portable instrument while also reducing logistical demands by eliminating the need for a helium supply. Methods Mass spectrometry was performed at pressures exceeding 1 Torr with ambient air as the buffer gas. A glow discharge electron ionization source and a miniature cylindrical ion trap mass analyzer with a radius of 0.5 mm were used. Mass analysis was possible at these pressures with increased radiofrequency (RF) drive frequencies (10 MHz) compared with commercial ion traps (~1 MHz). A differentially pumped chamber was used so that mass spectrometry could be performed at high pressures and detection performed at low pressures with an electron multiplier. Results HPMS with air buffer gas was demonstrated using a suite of volatile organic compounds (VOCs). The glow discharge ionization source was optimized for operation using air. Mass spectral peak widths increased a factor of 8 compared with helium, as expected, but useful chemical information was still acquired. A mixture of VOCs was detected with ambient air as the buffer gas, showing that valuable mass information can be gained using HPMS without the requirement of an onboard buffer gas source. Conclusions HPMS significantly reduces the pumping requirements required for miniature mass spectrometers and the use of ambient air buffer gas further reduces size, weight, and logistics requirements. Mass analysis at high pressures of ambient air is another important step for the development of hand portable mass spectrometers. Copyright © 2016 John Wiley & Sons, Ltd.