Cleaning a high-vacuum Penning gauge (cold cathode vacuum gauge) | Summary and Q&A

TL;DR

The video discusses the author's experience with their high vacuum Penning gauge, including its construction, troubleshooting, and refurbishment.

Key Insights

• ✋ The high vacuum Penning gauge is essential for monitoring vacuum levels in the scanning electron microscope.
• 😋 The use of a crushable metal seal provides a reliable vacuum seal without relying on rubber o-rings.
• 🥺 Rosin flux, although initially effective, can lead to outgassing and contamination over time.
• 🦭 Pure indium wire is a more suitable and long-lasting replacement for rosin flux in creating the vacuum seal.
• 🧲 The presence of magnets in the gauge creates a helical path for charged particles, improving accuracy.
• 😑 The rainbow colors observed on the metal shield of the gauge result from a film deposition caused by rosin flux and accelerated ions.
• 🦭 Cleaning and reassembling the gauge with the proper seal and addressing contamination are necessary for optimal performance.

Transcript

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Questions & Answers

Q: How is the high vacuum Penning gauge connected to the scanning electron microscope?

The author connects the high vacuum Penning gauge to their scanning electron microscope to monitor the vacuum level while the microscope is in operation.

Q: What is used to create a vacuum seal in the gauge?

Instead of a rubber o-ring, the gauge utilizes a crushable metal seal, which ensures a tight metal-to-metal contact and prevents leaks.

Q: What problems did the author face with the gauge?

The author used rosin flux as a substitute for the crushable metal seal, causing outgassing and contamination over time, leading to performance issues.

Q: How did the author fix the gauge?

The author purchased pure indium wire to replace the rosin flux. Indium is softer than lead and ensures a proper seal, preventing outgassing and contamination.

Summary & Key Takeaways

• The author explains how their high vacuum Penning gauge is connected to their scanning electron microscope to monitor the vacuum level while running the microscope.

• The gauge is constructed with a metal-to-metal contact and a crushable metal seal instead of a rubber o-ring to create a vacuum seal.

• The author encountered issues with the gauge due to the use of rosin flux as a substitute for the crushable metal seal, leading to outgassing and contamination.