In situ measurement of gas composition changes in radio frequency plasmas using a quartz sensor
- National Institute of Advanced Industrial Science and Technology, AIST, Tsukuba Central-2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan)
A simple method using a quartz sensor (Q-sensor) was developed to observe gas composition changes in radio frequency (rf) plasmas. The output depends on the gases' absolute pressure, molecular weight, and viscosity. The pressure-normalized quartz sensor output depends only on the molecular weight and viscosity of the gas. Consequently, gas composition changes can be detected in the plasmas if a sensor can be used in the plasmas. Influences imparted by the plasmas on the sensor, such as those by reactive particles (e.g., radicals and ions), excited species, electrons, temperature, and electric potentials during measurements were investigated to test the applicability of this quartz sensor measurement to plasma. The Q-sensor measurement results for rf plasmas with argon, hydrogen, and their mixtures are reproducible, demonstrating that the Q-sensor measurement is applicable for plasmas. In this work, pressure- and temperature-normalized Q-sensor output (NQO) were used to obtain the gas composition information of plasma. Temperature-normalization of the Q-sensor output enabled quartz sensor measurements near plasma electrodes, where the quartz sensor temperature increases. The changes in NQO agreed with results obtained by gas analysis using a quadrupole mass spectrometer. Results confirmed that the change in NQO is mainly attributable to changes in the densities and kinds of gas molecules in the plasma gas phase, not by other extrinsic influences of plasma. For argon, hydrogen, and argon-hydrogen plasmas, these changes correspond to reduction in nitrogen, production of carbon monoxide, and dissociation of hydrogen molecules, respectively. These changes in NQO qualitatively and somewhat quantitatively agreed with results obtained using gas analysis, indicting that the measurement has a potential application to obtain the gas composition in plasmas without disturbing industrial plasma processes.
- OSTI ID:
- 22051049
- Journal Information:
- Review of Scientific Instruments, Vol. 80, Issue 9; Other Information: (c) 2009 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
- Country of Publication:
- United States
- Language:
- English
Similar Records
Liquid Salts as Media for Process Heat Transfer from VHTR's: Forced Convective Channel Flow Thermal Hydraulics, Materials, and Coating
Chemical sensing system using plasma polymer films and pattern recognition algorithm
Related Subjects
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
ARGON
CARBON MONOXIDE
DISSOCIATION
ELECTRIC POTENTIAL
ELECTRODES
ELECTRON TEMPERATURE
GAS ANALYSIS
HIGH-FREQUENCY DISCHARGES
HYDROGEN
ION TEMPERATURE
MASS SPECTROMETERS
MOLECULAR WEIGHT
NITROGEN
PLASMA
PLASMA DIAGNOSTICS
QUARTZ
RADIOWAVE RADIATION
SENSORS
VISCOSITY