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JP-7855009-B2 - Vacuum feedthrough, electrode assembly, and apparatus for generating silent plasma discharge

JP7855009B2JP 7855009 B2JP7855009 B2JP 7855009B2JP-7855009-B2

Inventors

  • アンドレアウス，ベルンハルト
  • バルトナー，アストリット

Assignees

  • インフィコン・アーゲー

Dates

Publication Date
20260507
Application Date
20220321
Priority Date
20210331

Claims (9)

  1. A vacuum feedthrough (10) for an electrode assembly (20) for generating a DBD plasma discharge , wherein the following order is applied from the radial inside to the outside: Lens element (11) and A first ring (12) made of glass, A first hollow cylinder (13) made of a first dielectric material, A first conductive layer (18) and A second hollow cylinder (14) made of glass, A third hollow cylinder (15) made of ceramic, A second glass ring (16), It comprises a metal frame (17), A vacuum feedthrough (10) having at least one continuous radiation path for radiation from an optical wavelength range, starting from a first point on the first side (2) of the vacuum feedthrough, passing through the lens element, to a second point on the second side (3) of the vacuum feedthrough.
  2. Adjacent elements (11, 12, 13, 14, 15, 16, 17) are vacuum-tightly connected to each other to form a sealing surface (1) for separating the first side (2) and the second side (3) of the vacuum feedthrough from each other. In particular, the first conductive layer (18) made of platinum is applied to the outer surface of the first hollow cylinder. The first hollow cylinder and the first conductive layer protrude beyond the second hollow cylinder on the second side to form a conductive contact surface (19). The vacuum feedthrough (10) according to claim 1, wherein the first hollow cylinder, the second hollow cylinder, the third hollow cylinder, and the first conductive layer protrude beyond the lens element on the first side.
  3. The vacuum feedthrough (10) according to claim 1 or 2, wherein the lens element (11) is made of sapphire.
  4. The vacuum feedthrough (10) according to any one of claims 1 to 3, wherein the first hollow cylinder (13) is made of sapphire.
  5. An electrode assembly (20) for generating DBD plasma discharge, The electrode assembly comprises the vacuum feedthrough (10) according to any one of claims 1 to 4, and further comprises a fourth hollow ceramic cylinder (21) on its outer surface bearing a second conductive layer (22) particularly made of molybdenum, The fourth hollow cylinder (21) is positioned on the first side (2) of the vacuum feedthrough so as to be coaxial with the first hollow cylinder (13), and is at least partially located within the first hollow cylinder. The first conductive layer and the second conductive layer partially overlap along the axial direction. An electrode assembly (20) having a radially extending gap (24) open between the second conductive layer and the inner surface of the first hollow cylinder.
  6. The electrode assembly (20) according to claim 5, wherein the radial extension of the gap (24) is less than 1 mm, and in particular, the radial extension of the gap is 0.05 mm to 0.5 mm.
  7. A device (30) for generating DBD plasma discharge, The apparatus comprises the electrode assembly (20) according to any one of claims 5 or 6, The gap between the second conductive layer and the inner surface of the first hollow cylinder is hydrodynamically connected to the inside of the vacuum chamber. The first hollow cylinder and the first conductive layer protrude beyond the second hollow cylinder on the second side to form a conductive contact surface (19). The first conductive layer is electrically connected to the high-voltage AC power supply (32) at the conductive contact surface. The apparatus wherein the second conductive layer is electrically connected to earth.
  8. A measuring device (40) for characterizing pressure and/or gas composition, The measuring device comprises the device described in claim 7, A measuring device in which an optical sensor (41) is positioned on the atmospheric side (3) of the lens element (11).
  9. A method for operating the measuring device (40) according to claim 8, wherein an AC voltage having a voltage amplitude of 1 to 10 kV and a frequency of 1 to 10 kHz is applied between the first conductive layer (18) and the second conductive layer (22).

Description

This invention relates to a vacuum feedthrough, electrode assembly, and apparatus for generating silent plasma discharge. Furthermore, the invention relates to a measuring device for characterizing pressure and/or gas composition, and a method for operating the measuring device. This invention belongs to the technical field of plasma generation, generation of plasma light by ionization and excitation of molecules and ions, and measurement and evaluation of information regarding the gas composition of the generated plasma. One possible type of plasma discharge is the so-called DBD plasma discharge. (Also called silent discharge or dielectric barrier discharge (DBD)) DBD plasma discharge is an AC gas discharge in which at least one electrode is electrically isolated from the gas space by galvanic isolation using a dielectric. Because the insulator prevents the generation of arc discharge, DBD plasma discharge is also called dielectric suppression discharge. Measuring and evaluating light generated by DBD plasma presents numerous challenges. Device lifetime, sometimes vacuum suitability, apparatus size and complexity, and achievable sensitivity are significant obstacles. The objective of this invention was to solve at least one problem of the prior art. Specifically, one objective of this invention is to enable a miniature sensor for measuring pressure and/or gas composition based on DBD plasma discharge, and to provide a component suitable for this purpose. According to the present invention, this objective is solved by the vacuum feedthrough described in claim 1. Embodiments arise from the features of dependent claims 2 to 4. The vacuum feedthrough comprises the following elements, arranged radially from the inside outwards, in the following order: a lens element, a first glass ring, a first hollow cylinder made of a first dielectric material, a first conductive layer, a second glass hollow cylinder, a third ceramic hollow cylinder, a second glass ring, and a metal frame. The frame may be particularly annular. The frame can be made of stainless steel in particular. There is at least one continuous radiation path for radiation from the optical wavelength range, starting from a first point on the first side of the vacuum feedthrough and passing through the lens element to a second point on the second side of the vacuum feedthrough. The lens element is transparent to at least one wavelength range within the optical wavelength range and thus constitutes the optical portion of the vacuum feedthrough. The elements of the vacuum feedthrough are not obstructed when traveling along the path along at least one continuous radiation path, unless they are transparent in the aforementioned wavelength range. The optical wavelength range includes electromagnetic radiation with wavelengths from 100 nm to 1 mm, particularly visible light, ultraviolet, and infrared. The lens element may, for example, have the shape of a plano-convex lens, with the convex surface facing the first side of the sealing surface. The lens element may have, for example, a truss-head-shaped diameter-enlarging portion on the first side so as to radially overlap the first ring. In this way, radiation from the first side can be focused. For example, the lens element may be designed, by a combination of lens radius and refractive index, to focus parallel radiation from the first side to the second side focal point or at least the focal volume. In particular, the first side may be provided as the vacuum side, and the second side may be provided as the atmospheric side. In the context of this invention, the term "vacuum feedthrough" should be understood to mean that feedthrough is suitable for use in situations where there is a substantial pressure difference between the first and second sides, preventing gas from passing through the sealing surface to the other side. While this requirement is typical for feedthrough use in vacuum technology, it is also useful for other applications where vacuum-range pressures are not present on either side. Therefore, the vacuum feedthrough of the present invention is an electro-optical vacuum feedthrough. A first conductive layer, insulated from the frame, forms an electrical feedthrough. The lens element forms an optical feedthrough. If necessary, additional rod-shaped or wire-shaped electrodes can be passed through the lens element along its central axis. These additional electrodes can be fitted using a further glass ring. When power supply to additional elements is required, these additional electrodes allow the overall structure to remain compact. In one embodiment of the vacuum feedthrough of the present invention, adjacent elements (lens elements and further elements from the above list) are vacuum-tightly connected to each other so as to form a sealing surface that separates the first side, particularly the vacuum side, from the second side, particularly the atmospheric side, of the vacuum feedthrough. The first