Design method for molecular beam mass spectrum diagnosis apparatus

A design method and molecular beam technology, applied in the design field of molecular beam mass spectrometry diagnostic instruments, can solve problems such as difficulty in detecting non-stable species, difficulty in spectral analysis, etc., so as to reduce collision loss, improve signal-to-noise ratio, and improve pumping capacity Effect

Inactive Publication Date: 2004-09-01
DALIAN UNIV OF TECH
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Problems solved by technology

Spectrometry is suitable for the study of species with known spectra. The disadvantage is that spectral analysis is difficult and can only obtain information in a certain spectral range; mass spectrometry can give an overview of all components in the system at the same time, but conventional mass spectrometry can only be used for Active species in low-pressure plasma are used for diagnosis. When the pressure is high, it is difficult to detect unstable species due to collisions between particles.

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  • Design method for molecular beam mass spectrum diagnosis apparatus
  • Design method for molecular beam mass spectrum diagnosis apparatus
  • Design method for molecular beam mass spectrum diagnosis apparatus

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Effect test

Embodiment 1

[0024] Embodiment 1. High voltage pulse corona discharge N 2 +O 2 plasma diagnostics

[0025] Utilize the present invention to wire plate type high voltage pulse corona discharge N 2 (80%)+O 2 (20%) Positive ions in the cathode plate region of the plasma were investigated for diagnostics. The peak voltage and discharge repetition frequency of the positive high-voltage pulse power used in pulsed corona discharge are continuously adjustable in the range of 0-60KV and 0-200Hz, respectively, and the rising edge of the pulse voltage is between 20-50ns, and the pulse width (FWHM) Between 200-500ns. The reactor adopts a wire-plate structure. The positive corona wire is made of copper wire with a diameter of 0.5mm and a length of 50mm. The negative plate (ground) is made of a 20mm×20mm brass plate, and a small hole with a diameter of 150μm is opened in the center as a mass spectrometer. Sampling microholes, the corona wire and the small hole are facing each other with a distance ...

Embodiment 2

[0026] Embodiment 2. H in the dielectric barrier discharge plasma 3 - ion diagnostics

[0027] Utilizing the present invention, a larger concentration of H was observed for the first time under dielectric barrier discharge conditions 3 - Negative ions, an active species that has been disputed internationally for many years, have confirmed the stable existence of this species. In the experiment, the electrode structure was designed as a flat plate, the sampling hole plate was used as the ground electrode, and the diameter of the sampling hole was 300 μm. The high-voltage electrode was made of stainless steel plate, covered with quartz glass with a thickness of 5 mm, the discharge distance was 3 mm, and the power supply voltage was sinusoidal. Peak-to-peak voltage U p = 0-50kV, adjustable frequency 10k-35kHz.

[0028] attached image 3 Shown is the mixed gas of hydrogen and argon at a total pressure of 2.3Torr, U p = 40kV, H measured under the condition of discharge frequ...

Embodiment 3

[0029] Example 3. Diagnosis of Methane Dielectric Barrier Discharge Plasma

[0030]Utilize the present invention, measured the positive ion component in the methane dielectric barrier discharge synthetic diamond-like film process, the electrode structure is similar to embodiment 2, and difference is also covered with a Si with 1mm aperture in the center on the sampling orifice plate. base. Under the conditions of discharge frequency 1.4kHz, discharge peak-to-peak voltage 30kV, air pressure 0.7Torr, and electrode spacing 5mm, the measured CH 4 Dielectric barrier discharge plasma mass spectrogram, as attached Figure 4 shown.

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Abstract

The invention provides a method to design an active species diagnostic apparatus for high-air pressure plasm, and its character: it combines molecular beam sampling and mass spectrum techniques, adopts three-stage molecular pump to differentially pump air and at the same time adopt two-stage liquid nitrogen absorbing pump to further enhance the background vacuum, reducing the loss of active species, in addition adopt the beam split technique and combine with phase locked amplifier, enhancing the signal-noise ratio of system. It overcomes the disadvantage that the routine mass spectrum can detect the active species only at low air pressure, and has the advantages of wide working air pressure range, high detecting sensitivity, primarily obtaining full spectrum chart, etc.

Description

technical field [0001] The invention belongs to the technical field of plasma diagnostic equipment, and relates to a high-pressure plasma active species diagnostic instrument, in particular to a design method of a molecular beam mass spectrometer diagnostic instrument. Background technique [0002] With the development of low-temperature plasma technology, its application in the fields of microelectronics, environment, energy and materials has become an important sub-discipline with global influence, which has greatly changed some traditional processes. However, due to the complexity of the plasma itself, the mechanism is not completely clear even if a very mature plasma processing technology is used, and the theoretical simulation and calculation are also arbitrarily due to the lack of some important data. Therefore, plasma diagnosis has become an important means to study various microscopic processes in plasma. [0003] There are two main diagnostic methods for plasma act...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N23/22H01J49/42
Inventor 徐勇杨学锋朱爱民丁洪斌宋志民刘佳宏
Owner DALIAN UNIV OF TECH
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