The Effect of Surface Roughness on Supersonic Nozzle Flow and Electron Dispersion at Low Pressure Conditions
This study investigates supersonic flow within a nozzle under low-pressure conditions at the continuum mechanics boundary. This phenomenon is commonly encountered in applications such as the differentially pumped chamber of an Environmental Scanning Electron Microscope (ESEM), which employs an apert...
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MDPI AG
2025-07-01
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| Series: | Sensors |
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| Online Access: | https://www.mdpi.com/1424-8220/25/13/4204 |
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| author | Pavla Šabacká Jiří Maxa Robert Bayer Tomáš Binar Petr Bača |
| author_facet | Pavla Šabacká Jiří Maxa Robert Bayer Tomáš Binar Petr Bača |
| author_sort | Pavla Šabacká |
| collection | DOAJ |
| description | This study investigates supersonic flow within a nozzle under low-pressure conditions at the continuum mechanics boundary. This phenomenon is commonly encountered in applications such as the differentially pumped chamber of an Environmental Scanning Electron Microscope (ESEM), which employs an aperture to separate two regions with a great pressure gradient. The nozzle geometry and flow control in this region can significantly influence the scattering and loss of the primary electron beam traversing the differentially pumped chamber and aperture. To this end, an experimental chamber was designed to explore aspects of this low-pressure regime, characterized by a varying ratio of inertial to viscous forces. The initial experimental results obtained using pressure sensors from the fabricated experimental chamber were utilized to refine the Ansys Fluent simulation setup, and in this combined approach, initial analyses of supersonic flow and shock waves in low-pressure environments were conducted. The refined Ansys Fluent system demonstrated a very good correspondence with the experimental findings. Subsequently, an analysis of the influence of surface roughness on the resulting flow behavior in low-pressure conditions was performed on this refined model using the refined CFD model. Based on the obtained results, a comparison of the influence of nozzle roughness on the resulting electron beam scattering was conducted for selected low-pressure variants relevant to the operational conditions of the Environmental Scanning Electron Microscope (ESEM). The influence of roughness at elevated working pressures within the ESEM operating regime on reduced electron beam scattering has been demonstrated. At lower pressure values within the ESEM operating regime, this influence is significantly diminished. |
| format | Article |
| id | doaj-art-ab33d73b18cc4bfcb3d393c40fd2473d |
| institution | Kabale University |
| issn | 1424-8220 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | MDPI AG |
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| series | Sensors |
| spelling | doaj-art-ab33d73b18cc4bfcb3d393c40fd2473d2025-08-20T03:50:16ZengMDPI AGSensors1424-82202025-07-012513420410.3390/s25134204The Effect of Surface Roughness on Supersonic Nozzle Flow and Electron Dispersion at Low Pressure ConditionsPavla Šabacká0Jiří Maxa1Robert Bayer2Tomáš Binar3Petr Bača4Faculty of Electrical Engineering and Communication, Brno University of Technology, Technická 10, 616 00 Brno, Czech RepublicFaculty of Electrical Engineering and Communication, Brno University of Technology, Technická 10, 616 00 Brno, Czech RepublicFaculty of Electrical Engineering and Communication, Brno University of Technology, Technická 10, 616 00 Brno, Czech RepublicFaculty of Electrical Engineering and Communication, Brno University of Technology, Technická 10, 616 00 Brno, Czech RepublicFaculty of Electrical Engineering and Communication, Brno University of Technology, Technická 10, 616 00 Brno, Czech RepublicThis study investigates supersonic flow within a nozzle under low-pressure conditions at the continuum mechanics boundary. This phenomenon is commonly encountered in applications such as the differentially pumped chamber of an Environmental Scanning Electron Microscope (ESEM), which employs an aperture to separate two regions with a great pressure gradient. The nozzle geometry and flow control in this region can significantly influence the scattering and loss of the primary electron beam traversing the differentially pumped chamber and aperture. To this end, an experimental chamber was designed to explore aspects of this low-pressure regime, characterized by a varying ratio of inertial to viscous forces. The initial experimental results obtained using pressure sensors from the fabricated experimental chamber were utilized to refine the Ansys Fluent simulation setup, and in this combined approach, initial analyses of supersonic flow and shock waves in low-pressure environments were conducted. The refined Ansys Fluent system demonstrated a very good correspondence with the experimental findings. Subsequently, an analysis of the influence of surface roughness on the resulting flow behavior in low-pressure conditions was performed on this refined model using the refined CFD model. Based on the obtained results, a comparison of the influence of nozzle roughness on the resulting electron beam scattering was conducted for selected low-pressure variants relevant to the operational conditions of the Environmental Scanning Electron Microscope (ESEM). The influence of roughness at elevated working pressures within the ESEM operating regime on reduced electron beam scattering has been demonstrated. At lower pressure values within the ESEM operating regime, this influence is significantly diminished.https://www.mdpi.com/1424-8220/25/13/4204Ansys FluentapertureCFDdifferentially pumped chamberESEMlow pressure |
| spellingShingle | Pavla Šabacká Jiří Maxa Robert Bayer Tomáš Binar Petr Bača The Effect of Surface Roughness on Supersonic Nozzle Flow and Electron Dispersion at Low Pressure Conditions Sensors Ansys Fluent aperture CFD differentially pumped chamber ESEM low pressure |
| title | The Effect of Surface Roughness on Supersonic Nozzle Flow and Electron Dispersion at Low Pressure Conditions |
| title_full | The Effect of Surface Roughness on Supersonic Nozzle Flow and Electron Dispersion at Low Pressure Conditions |
| title_fullStr | The Effect of Surface Roughness on Supersonic Nozzle Flow and Electron Dispersion at Low Pressure Conditions |
| title_full_unstemmed | The Effect of Surface Roughness on Supersonic Nozzle Flow and Electron Dispersion at Low Pressure Conditions |
| title_short | The Effect of Surface Roughness on Supersonic Nozzle Flow and Electron Dispersion at Low Pressure Conditions |
| title_sort | effect of surface roughness on supersonic nozzle flow and electron dispersion at low pressure conditions |
| topic | Ansys Fluent aperture CFD differentially pumped chamber ESEM low pressure |
| url | https://www.mdpi.com/1424-8220/25/13/4204 |
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