Patent ID: 12209579

DETAILED DESCRIPTION

Provided herein are articles of manufacture, systems, and methods employing a gas-deflector plate in low to ultra-high vacuum systems that use differential pumping (e.g., gas-target particle accelerators, mass spectrometers, and windowless delivery ports). In certain embodiments, the gas-deflector plate is configured to be positioned between higher and lower pressure regions in a pressurized system, wherein the gas-deflector plate has a channel therethrough shaped and/or angled such that jetting gas moving through the channel from the higher pressure region to the lower pressure region enters the lower pressure region at an angle offset from the vertical axis of the gas-deflector plate. In other embodiments, a jet-deflector component is employed such that the jetting gas strikes such jet-deflector component and is re-directed in another direction.

In certain embodiments, the present disclosure provides a gas deflection technique to deflect supersonic jetting in differential pumping applications. In some embodiments, the deflection device is a gas-deflector plate with a channel with an asymmetric aperture. When high pressure gas is expanded through the channel and asymmetric aperture, the resulting gas jet (e.g., supersonic gas jet) gains an off-axis velocity component in the direction of the asymmetry. In particular embodiments, the shape and/or angle of the channel diverts the direction of the gas jet in a differential pumping system, decreasing mass transport to lower pressure sections while reducing pumping requirements to maintain a given stage pressure. In certain embodiments, deflection of the gas jet is further improved with the addition of a jet deflector component positioned in the direction of the aperture asymmetry.

In some embodiments, provided herein are systems, devices, and methods providing a jet deflection technique that mitigates the effects of supersonic and subsonic gas jetting in staged differential pressure applications. In certain embodiments, provided herein are gas-deflector plates that are angled and/or shaped (e.g., with an asymmetric aperture) which are combined with a jet deflector component to direct jetting gas off axis of the plate. In certain embodiments, such gas-deflector plates reduce mass transport between differential pumping stages, thus reducing pumping demands and/or permitting lower base pressures for a given configuration.

In certain embodiments, provided herein are systems, devices, and methods that improves the efficiency in differentially pumped systems. That is, using the systems, devices, and methods herein allows, for example, for greater pressure differential if all things are equal, or allows the same differential pressure using smaller and/or fewer pumps, or allows a greater aperture to exist between the high and low pressure regions. In certain embodiments, the systems, devices, and methods herein allows for larger aperture diameter to be used for a given pumping configuration.

Provided below is a description of certain exemplary embodiments depicted in the figures. It is to be understood that the applications of this invention are not limited to the such exemplary embodiments. Further, in particular embodiments, the gas-deflector plates and jet-deflector components described below are employed in an accelerator system like the ones described in U.S. Pat. No. 8,837,662, which is herein incorporated by reference in its entirety.

FIG.1Ashows a gas-target particle accelerator (25) with a pair of gas-deflector plates (30) between components with different pressures. An ion source (26) is connected to an accelerator (27), which is connected to a two differential pumping system with two stages (28). Each stage is connected to a vacuum pump (29). A target chamber (32), with an ion confinement magnet (31) therearound, is connected to the differential pumping system with a gas-deflector plate (30) in between. The lateral axis (40) of the gas-deflector plate is shown with a dotted line.

FIG.1Bshows a plate (50) with a uniform channel (1) that is straight through the plate.FIG.2shows the use of such a uniform channel (1) positioned between a higher pressure stage (2) and a lower pressure stage (3). As a result of using a uniform channel (1), the gas jet (4) from the higher pressure stage to lower pressure stage is not offset, and instead comes straight into lower pressure stage (3). When an aperture 1 is positioned between two stages of different pressure with stage (2) being at a higher pressure than stage (3), the difference in pressure between the two stages results in a gas flow between the stages that will tend to equalize the pressure in the two stages. Pumps can be employed that counteract this mass flow by transporting the gas escaping into the lower pressure stage back into the higher pressure stage, maintaining a pressure differential. Ultimately, the pressure differential that can be maintained between multiple connected regions depends on the pumping capacity of each region, and the size of the apertures between the two regions. A commonly observed phenomena that reduces the efficacy of coaxial differential pumping systems is the formation of gas jets between regions. If the pressures are sufficiently different between any two stages, the gas coming from the higher pressure region will form a jet as it enters the lower pressure region. The jet is a continuous, coherent, and directional flow of gas that can traverse a given pressure region and emerge in the subsequent pumping stage largely intact. The jet effectively “bypasses” a given pumping stage and, therefore, significantly decreases the efficacy of the differential pumping system. In the case of a three or more-stage system, a considerable portion of the jet can traverse the first differential pumping stage (3), reducing the efficacy of this stage while increasing upstream pressure and pumping requirements in stages (5) and (6).

Such gas jet bypass issues are addressed by the devices, systems, and methods described herein. The function of these devices, systems, and methods is to deflect the gas jet off axis and reduce or destroy its coherence so that the pumps in any given stage can act on the gas. For example, the gas-deflector plates herein with a channel angled or shaped (e.g., with an asymmetric aperture), results in a gas-jet with a velocity component off-axis direction of the aperture axis and/or the gas-deflector plate. This velocity offset, for example, is in the direction of the asymmetry shown by arrow (8) inFIG.3. The deflection limits the gas that is directly injected into the next differential pumping stage. In some embodiments, multiple configurations of this asymmetric aperture are placed in series between pumping stages to multiply this effect (seeFIG.1A).

FIG.3Ashows an exemplary gas-deflector plate (30) with a channel (70) with an asymmetric aperture (7) that causes the jetting gas (arrow;8) to deflect from the vertical axis (beam axis) of the gas-deflector plate.FIG.3Bshows the exemplary gas-deflector plate (30) fromFIG.3Awith dotted lines to show the longitudinal axis (40) and lateral axis (41). The longitudinal axis and lateral axis are perpendicular to the vertical axis (beam axis).

FIG.4shows an exemplary schematic of a three-stage differential pumping configuration with an asymmetric aperture (7) that causes jetting gas (arrow;8) to deflect downwards away from vertical (beam) axis. Boxes (3), (5), and (6) show differential pumping stages. Stage (2) is a higher pressure stage than stages (3), (5), and (6).

FIG.5Ashows an exemplary gas-deflector plate with a channel (70) with an asymmetric aperture (7) that causes the jetting gas (arrow;8) to deflect from the vertical axis (beam axis). The jetting gas hits a jet deflector component (10) causing the jetting gas to deflect to a different direction (arrow;12).FIG.5Bshows the exemplary gas-deflector plate (30) fromFIG.5Awith dotted lines to show the vertical axis (42) (aka “beam axis”).

FIG.6shows an exemplary schematic of a three-stage differential pumping configuration with an asymmetric aperture and a jet deflector component (10) that causes the jetting gas to travel in a different direction (arrow;12) offset from the vertical axis (beam axis). Boxes (3), (5), and (6) show differential pumping stages. Stage (2) is a higher pressure stage than stages (3), (5), and (6). The addition of the jet deflector component provides additional deflection of the gas jet shown by arrow (12).

FIG.7illustrates the use of a channel (70) with asymmetric aperture for gas jet deflection in particle accelerator applications. The particle beam is shown as dotted line (14). Using a particle accelerator as shown in this figure, particles are accelerated into a high-pressure gas (or plasma) target (13) of enough length to decelerate the particle beam shown by arrow (14). The pressure in the target is higher than differential pumping stages (15), (16), and (17). The incorporation of a channel (70), with an asymmetric aperture between the target and adjacent differential pumping stage, results in reduced pumping requirements and lower base pressures in stages (15), (16), and (17). The incorporation of a jet deflector component further reduces the gas transport between the target and connected differential stages.

FIG.8illustrates the use of a channel (70) with an asymmetric aperture for gas jet deflection in a mass spectrometer. A mass spectrometer is composed of a sample chamber (19) separated from an ionization chamber (20) by differential pumping stages (21) and (22). An asymmetric aperture located between stages (19) and (21) deflects gas, enabling the sample chamber to operate at a high pressure, the ionization chamber to operate at high-vacuum levels, while generally eliminating the gas jetting phenomenon which would ordinarily result between stages (20), (21), and (22).