Beam current stability is crucial for accurate quantitative analysis in electron microprobe systems. A stable beam ensures consistent X-ray intensity, which is essential for accurate element quantification. Fluctuations in beam current can lead to inaccurate intensity measurements, affecting the reliability of quantitative analysis.
In this article, we highlight a recent collaborative effort between SEMTech Solutions, Inc., Advanced Microbeam, Inc. and Concord University Materials and Rare Earth Element (REE) Analysis Center. The primary objective of the project was to modernize the existing Applied Research Laboratories (ARL) SEMQ electron probe microanalyzer (EPMA) at Concord University. The modernization focused on enhancing image quality, upgrading system electronics, and integrating software running on a Windows 11 user interface. All of this was achieved; however, the real benefit was the improvement made in achieving tighter beam current tolerances. By introducing new power supplies and interfacing them with the ARL SEMQ column via a customized version of the SEMView8000, the team achieved tighter beam current tolerances than were previously possible on this legacy instrument. As a result, the refurbished system, now named the SEMQ 8000 (Figure 1), can deliver beam stability on par with modern EPMA instruments.
Further details on this collaboration are available in a recent press release issued by Concord University.
Figure 1. ‘SEMQ 8000’ EPMA Powered by SEMView8000
Beam Current Stability Overview:
For modern newer electron probe microanalyzers using a tungsten (W) filament electron gun, the typical probe current stability specifications are +/- 0.05% per hour and +/- 0.3% over a 12-hour period. The original equipment manufacturer probe current stability of the ARL SEMQ electron probe microanalyzer using a tungsten gun is +/- 1% over an 8-hour period, which is now easily met.
While the stability characteristics will vary based on the instrument’s age, maintenance, and environmental conditions, the goal for high quality analytical results is to minimize probe current drift and maintain a stable beam. Factors like accelerating voltage, beam diameter, and counting time also influence the results of quantitative analysis, but beam stability is a fundamental aspect of achieving accurate and reliable results.
The high-voltage gun supply incorporated into the SEMView8000 is designed to maintain a stable accelerating voltage. Also, the beam current stabilizer, as shown in Figure 2, is a feedback circuit which controls condenser lens 2 in the microprobe column and is also crucial in maintaining stability of the beam current with the SEMQ 8000.
Graph 1. Concord University Beam Current vs. Time
SEMQ 8000 Beam Current Measurement Results:
Review of the beam current measurements made over an eight-hour period in Graph 1 shows a rise in beam current over the first two hours then settling down. The settling period, from 2 to 8 hours, is extremely stable and offers the most consistent time for analytical results. The beam current measured in this 2 to 8 timeframe is +/- 0.05%, the exact same specifications as posted with newer systems. Taking the total beam current curve over an eight-hour period shows that we are now well within the +/- 1%.
SEMQ 8000 Control Software Enhancements:
While the software user interface of the SEMQ 8000 EPMA is the same as that of the SEMView8000 UI, there were some underlying changes made to incorporate the addition of a second condenser lens, both in hardware and software as depicted in Figure 2. The SEMQ 8000 Microprobe tab provides status information and controls condenser lenses 1 and 2. Additionally, a checkbox option has been added to allow the operator to enable or disable the Secondary Electron Detector (SED).
Figure 2. ‘SEMQ 8000’ Microprobe Schematic and SEMView8000 Software Control Tab
Summary:
Incorporation of the SEMTech Solutions SEMView8000 has improved the beam current tolerances on a well-maintained ARL SEMQ EPMA system at Concord University, elevating its performance. Maintaining a stable beam current involves careful tuning of the electron gun parameters, including accelerating voltage, filament current, and lens excitation, which the SEMView8000 drives and controls. Accurate quantitative analysis in electron microprobes relies on measuring the intensity of characteristic X-rays emitted by the sample. A stable beam current ensures that the number of X-rays generated is directly proportional to the concentration of the elements in the sample.
The SEMView8000 Difference:
In addition to offering exceptionally stable electronics, the SEMView8000 offers a user-friendly interface, making it easy for both experienced and novice users to run any electron beam system.
A key advantage of the SEMView8000 is its Windows 11 compatibility. Many legacy scanning electron microscopes (SEMs) and electron probe systems run on outdated operating systems, making integration with modern data processing and analysis tools challenging. By upgrading these systems with SEMView8000, users gain access to a modern, stable, and secure computing environment with expanded functionality, improved processing power, and ongoing software support.
Another standout feature of the SEMView 8000 is its high-resolution imaging capabilities. By capturing images in 8K resolution, users can zoom in on intricate sample features without losing detail. This exceptional level of clarity ensures that even the smallest structural elements can be analyzed with confidence.
By combining advanced control electronics, modern software integration, and cutting-edge imaging, the SEMView8000 transforms aging electron beam instruments into powerful, high-performance tools capable of meeting the demands of today’s research and industrial environments.
Ready to Get Started with the SEMView8000?
If you’re considering an upgrade for your existing SEM or EPMA, we’re here to help. Our team is ready to assist you in optimizing your workflow, improving measurement accuracy, and maximizing the potential of your SEM system.
If you have questions or would like to learn more about the SEMView8000’s capabilities, reach out to us today. We’d be happy to discuss your specific requirements and guide you through the upgrade process.
For detailed information on converting your EPMA system, reach out to Advanced Microbeam.
