X-ray thickness gauging is pivotal in online control applications, providing real-time measurements to maintain product quality and consistency. This post delves into the fundamental physics underpinning this technology, primarily the Beer-Lambert Law, which relates to the attenuation of X-rays passing through a material to its thickness. Understanding this principle is essential for effectively utilizing and optimizing X-ray thickness measurement systems in various industrial processes.

Understanding the Beer-Lambert Law

The Beer-Lambert law relates to the attenuation of photons through a material. In the case of X-ray thickness gauging, this relationship can be used to determine the thickness of a known material by shining some fixed quantity of X-ray photons through the material through a detector. Some of these X-rays will be absorbed in the material, and the rest will hit the detector. By counting these “missing” X-rays, the thickness of the material can be accurately determined.

The Beer-Lambert law is typically expressed as:

Where

Setting up the Equation: Arranging for x

Because we’re interested in the thickness of the material, we can rearrange the equation to solve for the thickness as follows:

Setting up the Equation: Defining the Constants

In the equation above, the initial intensity \(I_0\) and attenuation coefficient \(\mu\) are constants.

The initial intensity can be defined as the number of X-ray photons read by the detector with no material present. Complex variables related to the X-ray tube itself, the geometry of the measurement system, and the efficiency of the detector all contribute to the initial intensity of the measurement system. For this reason, \(I_0\) is generally measured in situ in the final machines. Also, the tube and detector efficiencies can change slightly over time, so periodic recalibration of the initial intensity is recommended.

The mass attenuation coefficient, \(\mu\), can also be thought of as a constant for a given material and measurement system. This value varies with material composition and X-ray energy, necessitating referencing databases such as the NIST X-Ray Mass Attenuation Coefficients database. For practical applications, especially with varying X-ray photon energies such as in bremsstrahlung radiation produced by an X-ray tube, integrating these tables over the energy spectrum is essential. This integration acknowledges the range of X-ray energies produced, ensuring the calculated thickness accounts for the entire X-ray spectrum. Again, because of the complexities of these calculations, in practice these numbers are often empirically defined by using coupons of the materials under test at calibrated thicknesses to calculate the mass attenuation coefficient. This can be achieved with a simple rearranging of the now-familiar formula:

By running the system with no sample, and with several samples of known thickness, we can empirically determine both the initial intensity of our measurement system, as well as the mass attenuation value for the material we’ll be measuring.

Solving for x: Calculating the Thickness

At this point in the process, we have our initial intensity, \(I_0\), and our mass attenuation, \(\mu\), defined for the material we’re testing. All that’s left now is to shine the X-rays through the sample, measure the X-rays at the detector, \(I\), plug in the variables, and solve for \(x\).

Calculating the thickness in real-time enables truly closed-loop process control in thin film production environments. The thickness can be fed back in real time to the control systems overseeing the line speed to either slow down or speed up the line to maintain the desired thickness within the required tolerance.

Why MXR’s X-Ray Tubes Excel in Thickness Measurement

MXR’s X-ray tubes stand out in thickness measurement applications due to their highly stable X-ray flux, ultra-low leakage current, and highly repeatable process. These features ensure that the initial intensity remains consistent, a crucial factor for accurate applications of the Beer-Lambert Law in real-time control systems.

Stability in X-ray flux minimizes the variability in measurements, leading to high precision, while the low leakage current reduces noise, further enhancing measurement accuracy. This combination makes MXR’s tubes exceptionally reliable for precision thickness gauging applications.

At MXR, we understand the critical importance of precise thickness measurements in maintaining product quality. Our X-ray tubes are engineered for exceptional stability and low leakage current, ensuring adherence to the Beer-Lambert Law and enabling high-precision gauging. Transform your measurement process with MXR’s reliable technology. Contact us today to find out how our X-ray solutions can refine your quality control and enhance your operational accuracy.

The post Use Case Deep Dives: X-ray Thickness Gauging appeared first on Micro X-Ray.

A Quick Refresher on EDXRF

Energy Dispersive X-Ray Fluorescence (EDXRF) is a non-destructive analytical technique used to determine the elemental composition of various materials, ranging generally from Al – U (with higher end spectrometers pushing those boundaries). A sample is excited with a primary X-ray beam, which causes a secondary beam to be emitted (or fluoresced) which is characteristic of the elements present. EDXRF collects this secondary beam, measuring the energy of each of these emitted X-rays, and collecting the X-rays into a spectrum. This spectrum is then analyzed to enable precise identification and quantification of the elements. This method stands out for its versatility, allowing analysis of solids, liquids, and powders across a wide range of concentrations, from major components to trace elements. Its key advantages include rapid analysis times, minimal sample preparation, and the ability to analyze samples in their natural state, making EDXRF a valuable tool in fields such as material science, environmental testing, quality control, and archaeological studies.

High-quality X-ray tubes, like those developed by Micro X-Ray, are crucial for achieving accurate and reliable EDXRF results. They enable more precise elemental analysis by offering optimized flux, advanced cooling methods for longer tube life, and the flexibility to adapt to various analytical needs, thereby supporting a wide array of research and industrial applications.

The Perfect Balance: 50kV/50W

Achieving the ideal balance between adequate power for a robust secondary fluorescence while avoiding detector flooding is key in EDXRF. The 50kV/50W specification serves as a sweet spot for XRF tubes, ensuring clear, distinct spectral peaks for more reliable data in around 90 seconds or less. Some applications benefit from slightly higher voltages, and some applications benefit from higher powers, but the 50kV/50W XRF tube has proven to be a standard specification in EDXRF machines for many years.

Lightbright End Window Tube: Maximizing Precision

The Lightbright end window tube, designed for precision and efficiency, features a large cone angle an ideal takeoff angle to maximize usable flux. Ultra-thin window options, as thin as 50μm, reduce low energy absorption, capturing even the subtlest spectral lines. Its end window geometry facilitates close source/sample/detector arrangements, optimizing detection efficiency. Integrated o-ring grooves support helium or vacuum purge capabilities, maintaining spectral purity and minimizing background noise.

Mini-Focus Packaged Tube: Redefining Versatility and Reliability

Our mini-focus packaged tube has been designed with an industry-standard form factor, allowing for easy drop-in replacements in both laboratory and field settings. Thanks to a proprietary oil filling technique, it can be mounted in any orientation without arcing, ensuring consistent performance. The integration of a high voltage (HV) cable reduces failure risks by removing the high voltage well connection point, enhancing device reliability and enabling quick and easy maintenance.

SeeRay: Fast Focal Spot Stabilization and Detailed Spatial Resolution

The SeeRay stands out for its rapid spot stabilization time, ideal for use with X-ray optics. Compatible with our diamond anode technology and featuring spot sizes down to 50μm and power loading up to 1.5W/μm, it enables fast, spatially resolved EDXRF measurements when combined with polycapillary optics. This capability allows for quick and detailed elemental mapping, offering a considerable advantage in both industrial and academic applications.

Extended Lifetime and Lower Total Cost of Ownership (TCO)

A pivotal factor in the selection of X-ray tubes is their operational lifetime and the subsequent total cost of ownership (TCO). Both the Lightbright and SeeRay tubes feature direct anode cooling paths, while the Mini-Focus tube utilizes an efficient oil-to-brass cooling method. These cooling approaches significantly extend the service life of our tubes beyond that of competitive offerings. A longer service life not only means lower TCO but also fewer service visits, minimizing downtime and enhancing productivity. For a deeper dive into the longevity of our X-ray tubes, please refer to our detailed blog post on how long your X-ray tube will last.

Revolutionizing EDXRF with Micro X-Ray

Micro X-Ray is dedicated to pushing the boundaries of EDXRF analysis through technological innovation and excellence. Our Lightbright end window, Seeray, and mini-focus packaged tubes are tailored to meet the varied needs of the scientific community, enhancing precision, efficiency, and innovation in analysis.

Explore the potential of our advanced tube technologies for your EDXRF applications. With Micro X-Ray, embark on a journey towards groundbreaking scientific discovery, leveraging our cutting-edge solutions to shape the future of analysis.

Thank you for considering Micro X-Ray as your partner in advancing EDXRF analysis. We are eager to support your research and development efforts with our state-of-the-art technologies.

We are here to provide the tools and insights necessary for navigating the complexities of EDXRF analysis. For further information or to discuss how our technologies can cater to your specific research needs, please don’t hesitate to reach out. Together, let’s drive innovation and achieve exceptional breakthroughs in the field of scientific analysis.

The post Use Case Deep Dives: Empowering EDXRF Analysis with Micro X-Ray Tubes appeared first on Micro X-Ray.

A traditional anode in an X-ray tube consists of a relatively large piece of copper, topped with a relatively thin brazed disk of some target material, often Tungsten. While effective, this design has limitations in power dissipation and achievable spot size. The entire power of the X-ray beam is being dumped into an area the diameter of the spot, and just a few microns thick. Because X-ray generation is a notoriously inefficient process, well over 99% of the beam power must be dissipated as heat in that small volume, then wicked away by the copper anode substrate. A standard Tungsten target, for example, can handle about 1W/μm of spot size before becoming overloaded. If this power loading is exceeded, the target can evaporate and pit in a matter of seconds.

Micro X-Ray’s innovative diamond anode change this dynamic, adding a diamond layer to the target assembly to effectively move heat out of the X-ray spot and in to the bulk copper anode. This unique anode design allows for up to 50% higher power loading when compared to a standard anode design. In the case of Tungsten, our diamond substrate enables power loading of up to 1.5W/μm, allowing brighter flux in a smaller spot than any other fixed anode tube on the market.

Microbox – Micro-Precision Imaging Redefined

In our Microbox product line, the integration of diamond substrates into the anode design has been a game-changer. This advancement enables up to 50% higher power loading in the focal spot compared to traditional copper anodes, yielding 7.5W of power in our 5μm focal spot.

Key Advantages of the Diamond Anode Microbox

• Ultra-Crisp Images: With focal spot sizes down to 5μm, the Microbox enables industry leading image clarity.
• Enhanced Efficiency: The superior thermal dissipation of diamond allows for more consistent and prolonged high-power operation, delivering 7.5W of power in the 5μm spot.
• Broad Application Spectrum: This level of precision and power opens new avenues in non-destructive testing, electronics inspection, and material science.

SeeRay – Powering High-Flux Applications and Unleashing Unprecedented Brightness in Compact Form

The SeeRay stands out for its ability to produce super bright 50μm spots running at 75W, a feat made possible by MXR’s diamond anode technology. This exceptional flux brightness, unusual for its size, is enables true market differentiation in microXRF and XRD machines.

Key Advantages of the Diamond Anode SeeRay

• Massive Flux Output: The combination of high power and an optic provides a flux that well exceeds expectations for a tube of this size.
• Versatility in Applications: Ideal for high-end research and industrial applications requiring intense brightness and precision.
• Sustainable and Efficient: The diamond substrate not only boosts performance but also contributes to longer lifespan and reduced operational costs.

Pioneering the Future of X-ray Technology

As we continue to celebrate our journey in the #MXRDecadeOfInnovation, the advancements in our Microbox and SeeRay products stand as testaments to Micro X-Ray’s commitment to pioneering the future of X-ray technology. By harnessing the unique properties of diamond substrates, we have not only overcome traditional limitations but also opened a new realm of possibilities in precision imaging and high-flux applications.

The Impact of Innovation

• Setting New Standards: Our breakthroughs in anode technology set new benchmarks in the industry, pushing the limits of what’s possible in compact, finely focused X-ray sources.
• Empowering Industries: From research labs to industrial quality control, our innovations empower professionals with tools that transform their capabilities and efficiency.
• Driving Forward: Each advancement is a step towards more sustainable, efficient, and powerful X-ray solutions, keeping us at the forefront of technological evolution.

Join Us on This Exciting Journey

We invite you to be a part of this exciting era of innovation. Explore how our cutting-edge X-ray solutions can elevate your work to new heights of precision and efficiency. Whether you are looking for advanced imaging capabilities with the Microbox or require the high-flux performance of the Seeray, our team is ready to assist you in finding the perfect solution.

Get in Touch

– Discover more about our products: Visit our website or contact our sales team at sales@microxray.com.

– Need assistance? Reach out to our support team at support@microxray.com or call us at 831-207-4900.

– Stay updated: Follow us on LinkedIn for the latest news and innovations.

Let’s embrace the future of X-ray technology together. #MXRDecadeOfInnovation

The post Decade of Innovation: Revolutionizing Anode Technology with Diamond Substrates appeared first on Micro X-Ray.

Most users of X-ray tubes intuitively understand that X-ray tube lifetime is finite, and that X-ray tubes are consumable items due to the lightbulb-like filament that is generally used as an electron source. One of the first questions when dealing with any consumable is, how long will it last? This question informs total cost of machine ownership, preventative maintenance schedules, and a number of other key decisions needed to accurately compare one source against another.

In today’s post, we’ll look at the common failure modes of X-ray tubes, what can be done to manage them, how long your tube might be expected to last in the field, and why it’s a surprisingly hard question to answer.

A Brief Review

X-ray tubes are vacuum devices, meaning they require a high vacuum to operate. This high vacuum is needed for high voltage insulation, but it is also useful in allowing the electrons to travel from the cathode side of the X-ray tube to the anode, in order to generate X-rays. With a lower quality vacuum, the journey from cathode to anode becomes more challenging for the electrons, and therefore the filament must be run harder. For more information on this phenomenon, please see our previous articles on how X-rays are generated.

All of Micro X-Ray’s X-ray tubes are sealed type X-ray tubes. Sealed tubes are (as the name suggests) completely vacuum sealed at manufacturing, and contain no user-serviceable parts. This makes an extremely compact, robust, and durable package compared to their open type counterparts.

Filament Failure

The first failure mode to explore is failure of the filament. Modern X-ray power supplies control the beam current by tightly controlling the current through the X-ray filament. As the filament current increases, more electrons are released from the filament itself, and as more electrons are available inside the tube, more of them cross the high voltage gap to the target material, increasing the beam current. Over time, this electron emission wears down the filament, leading to an eventual end of life failure where the filament breaks completely – just like an Edison lightbulb. The lower the filament current, the longer the X-ray tube will last. The effect is a classic exponential curve – as an example, the standard 1.7A MXR filament has an estimated life of 100,000,000 hours at 1.34A, dropping to just 10,000 hours when run at the filament current limit of 1.7A. If the filament is run over the limit, say at 2.2A, it would break in a matter of seconds.

Other electron sources, for example dispenser cathodes like those used in the Microbox, have an ever longer service life than a filament-based X-ray tube.

Vacuum Degradation

Vacuum degradation is the other main cause of X-ray tube end of life. The metal components inside the X-ray tube outgas over time; this is an unavoidable law of physics, and while MXR’s X-ray tubes are built and processed with an eye towards minimizing this outgassing and improving the quality of the vacuum before sealing, the nature of sealed tubes means that not only can no gasses enter the tube, but none can escape either. As the tube heats up, the rate of outgassing internally increases.

As the vacuum degrades (meaning the pressure increases inside the X-ray tube), several things start to happen concurrently. First, the high voltage stresses inside the tube increase, which can lead to increasing leakage current, instability, and eventually arcing.

In addition to leakage increasing, the electrons from the filament have a higher change of hitting gas molecules as they traverse the high voltage gap between the anode and cathode. If an electron hits a gas molecule, it is knocked off course and loses energy, so it may not hit the target and produce an X-ray. As the vacuum degrades, therefore, the filament will need to be run hotter to compensate for those lost electrons in order to maintain a constant beam current. Over time, this process runs away, and the filament will eventually exceed its limit and open.

Race to the Death

What we have is a race to the death. As the vacuum degrades, the filament needs to work harder to keep up. As the filament works harder, the tube heats up more which causes the vacuum to degrade faster. What will happen first, will the filament run so hot it burns itself out? Or will the tube vacuum deteriorate so much that the high voltage arcs to ground, causing internal damage. There’s no one right answer, it could be either. If you’re running low kV/high current, it’s likely that the filament will burn out first. If you’re running high kV/low current, it’s likely that arcing due to vacuum degradation will occur first.

So…How Long Will my X-ray Tube Last?

10,000 hours is a good starting point for a lifetime estimate. Unless you run it hot, in which case it can be significantly less. Or, if you keep it cool, it can last longer. And of course you can’t run the filament (or cathode) too hard. If you run the filament conservatively, and keep the tube cool, it could easily last for 10x the 10,000 hour rule of thumb or more.

In practice, MXR has X-ray tubes in the field that are over 10 years old. These are usually in lab environments with a controlled atmosphere, minimal duty cycles, and adequate heating while operating. If you treat your X-ray tube well, it can last a long, long time. On the other hand, if you run 24/7 in a non-climate controlled factory in a hot part of the world, your tube just isn’t going to last as long as in the laboratory use case.

What can I do?

You can keep your tube cool! There’s not much to do about the filament other than ensure it doesn’t exceed the filament current limit, but for most tubes, the filament can live into the millions of hours before being depleted from normal operating conditions. So we’re left to focus on the outgassing, which can be minimized by keeping the tube cool. The cooler the internal components are, the slower the rate of outgassing. With a properly cooled X-ray source running within its design specifications, the lifetime of the tube can reliably exceed 10,000 hours, and often much, much more.

Contact Miro X-Ray Today

As always, let’s talk about it. Our engineers are always happy to have a conversation about YOUR application to help pick the right tube, and provide recommendations for the right cooling system.

The post X-Ray Sources 101: How Long Will My X-ray Tube Last? appeared first on Micro X-Ray.

Introduction

Since our founding 10 years ago, Micro X-Ray has been at the forefront of providing high-quality, innovative X-ray solutions. Our journey has been marked by a deep commitment to excellence and a consistent focus on meeting the evolving needs of industry leaders.

At the core of our commitment is a dual focus: a drive to understand our customers’ use cases and provide the right X-ray source for every application, and an industry-leading 6-week lead time on all orders. These two pillars showcase our unmatched efficiency and deep dedication to customer needs.

A Decade of Innovation: Micro X-Ray’s Journey

Over the last decade, Micro X-Ray has carved a niche in the X-ray technology sector, standing out not as a newcomer, but as a seasoned innovator. Our journey has been fueled by a relentless pursuit of excellence and a keen understanding of the industry’s needs. This experience positions us uniquely to offer bespoke solutions that cater precisely to the demands of industry leaders.

Six Weeks to Success: Our Lead Time Commitment

Understanding the critical role of time in business operations, we have streamlined our processes to deliver on a key promise – a 6-week lead time for all new orders, and often as short as two weeks for small quantity orders. This rapid turnaround is not just a service feature; it’s a reflection of our operational efficiency and our commitment to keeping our clients’ projects on track.

This 6-week lead time pledge underscores our understanding of the market dynamics and our dedication to being a reliable partner to industry leaders. Whether it’s for a critical healthcare application or a time-sensitive industrial project, our clients can count on us for short, reliable lead times and the highest quality standards.

Vertical Integration: A Decade of Continuous Improvement

Our approach to minimizing lead times while maintaining the highest standards of quality and consistency in our products is through vertical integration. By constantly monitoring and improving every aspect of our production process and deploying automation everywhere we can, we ensure that each product leaving our facility meets our rigorous standards. This method has been a cornerstone of our operations for the past decade, allowing us to provide products that industry leaders can rely upon for their precision and reliability.

Adapting to Industry Needs: Tailored Solutions

Our ten years in the industry, combined with our deep bench of seasoned industry experts, have given us deep insights into the unique challenges and requirements of different sectors. Leveraging this expertise, we offer customized solutions that are not just effective but are also aligned with the specific needs of each industry leader we serve. Our ability to tailor our solutions has been a key factor in our enduring relationships with clients across the highly fragmented low power X-ray marketplace.

Conclusion

As we reflect on our ten-year journey, Micro X-Ray stands as a beacon of innovation and reliability in the X-ray technology sector. Our commitment to a 6-week lead time and customized solutions demonstrates our dedication to being a pivotal partner for industry leaders. We invite you to experience the Micro X-Ray difference and join the ranks of our satisfied clients.

If you’re ready to explore what Micro X-Ray can do for you, we encourage you to reach out. Our team is eager to discuss your specific needs, how we can tailor our solutions for you, and arrange a tour of our cutting-edge facility in California. Contact us today through our web form, send us an email at sales@microxray.com, or call us directly at 831-207-4900. Let’s embark on a journey of X-ray excellence together, and start the next Decade of Innovation together.

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When you’re using an X-ray tube, it’s important to set the right parameters. First, there’s the excitation voltage of the tube, usually expressed in kV. Next, there’s the beam current of the tube, usually expressed in mA. If you multiply the two together, you can get the X-ray tube’s power. (Need a refresher? Check out this article)

What is Filament Current, Anyway?

So that’s the excitation voltage and beam current, but most high voltage power supplies also have a filament current limit and filament current pre-heat. What are those, and how do they relate to the beam?

One trick: because kV is V*10^3, mA is A*10^-3, and power is P=V*A you can easily calculate power in your head because 10^3*10^-3 reduces to exactly 1, so the power of the tube is just the integer kV value times the integer mA value. A tube running at 50kV and 1mA, therefore, runs at 50*1=50W. A tube running at 25kV and 0.5mA is running at 25*0.5=12.5W.

To answer this question, we need to remember how X-ray tubes work. The beam isn’t controlled directly, but rather it’s generated when electrons at (or near) the ground potential see a high potential on the anode, and try to equalize the potential difference by accelerating towards that high potential. In filament-based X-ray tubes, those electrons are a result of thermionic emission of a filament, and the thermionic emission is created as a result of running a current through the filament itself, similar to a traditional Edison lightbulb. The more current running through the filament, the hotter the filament is and the more electrons are released through thermionic emission.

Filament Current Control

The filament current is tightly controlled by the power supply based on the HV and beam current demand. The higher the beam current demand, the higher the filament current runs. The higher the kV at a given beam current operating point, the lower the required filament current to achieve the beam current set point. Regulating these interdependent control loops is the job of the X-ray power supply, which generates the high voltage required to produce the demanded excitation voltage, and regulates the filament current in order to produce the demanded beam current.

In order to produce a cloud of electrons, the filament must be hot enough to overcome the work function of the filament and enter the thermionic emission region, but if it’s too hot the filament itself will sublimate and eventually fail. Because thermionic emission is exponential with temperature, even small changes of just a few thousandths of an amp in the filament can produce huge swings in the amount of electrons in the cloud, and therefore in the beam current. For most Micro X-Ray filament tubes, emission often starts at ~1.2A, and exceeding ~1.8A can cause the filament to break in a matter of seconds. For this reason, filament current control loops are generally very stable DC currents.

Because filament control loops are often quite slow as a way to preserve the life of the filament and prevent overshoot, X-ray power supplies come equipped with two important settings: filament pre-heat and filament maximum. The pre-heat holds the filament at some fixed current below the emission threshold, which helps to reduce start-up time when X-rays are demanded. The filament maximum prevents the power supply from applying more than a certain amount of current to the filament to ensure a long service life. For most Micro X-Ray tubes, 1.0A is the recommended pre-heat setting, and 1.7A is the recommended maximum current limit setting. These settings reduce turn-on time while preserving the life of the filament.

What Power Supply Should I Use?

Selecting a power supply that can provide a stable beam current, filament current, and high voltage is critical to ensuring a long service life for your X-ray source. An integrated solution like the Microbox provides all the needed control, with a simple digital interface and 24V input requirement. For stand-alone systems, Micro X-Ray is pleased to provide a variety of power supply solutions depending on your exact application requirements. Reach out today for more information.

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One of the most misunderstood aspects of X-ray tubes is how the electron beam is shaped internally, and what impact that has on the X-ray spot. As a rule of thumb, for spot sizes above approximately 50 microns, the electron beam can generally be passively focused through a combination of emitter geometry and smart electron gun design. For spot sizes below that 50 micron threshold, or for applications where the flux distribution within the spot is important, more active measures must be taken. In this case, tube designers often use a grid voltage which modifies the electrostatic field around the electron beam, causing the electrons to change their trajectory mid-flight.

Depending on the tube designer, these electron beam shaping devices may be called apertures, grids, or focusing optics (not to be confused with external optics which act on the X-ray beam). Depending on the tube design and spot size requirement, one or more focusing optic element may be required to achieve the customer’s required beam size and shape. It’s important to understand that these focusing optics don’t create new electrons or increase the total flux output of the tube in any way. Rather, they simply re-route the electron beam in flight so it lands in a different spot on the X-ray target than it otherwise would.

In the case of a Minifocus tube such as our Seeray, adding a single grid voltage can concentrate the flux into a smaller spot, which can be beneficial in certain applications. For instance, when coupling a Minifocus tube to an external polycapillary X-ray focusing optic, the addition of a single grid voltage inside the tube can help concentrate the available flux in the center of the spot, enabling more efficient use of the optic.

But What Does a Grid Actually Do?

Let’s take the example of a single grid on a Minifocus X-ray tube.  The cathode of the tube is ground-referenced, and the anode of the tube is at a high voltage. As electrons are emitted from the tube’s filament, they are effectively at a 0V potential. They “see” the high voltage of on the tube’s anode, and race towards it to equalize the potential difference. The stream of electrons flowing from the cathode to the anode forms the electron beam. Because these electrons are at 0V, we have the ability to shape them as they move towards the anode by manipulating the electrostatic field they fly through with a relatively low grid voltage. Using this principal, MXR is able to design the electrostatic field they pass through in order to manipulate their landing pattern on the target, which forms the X-ray spot.

First, let’s look at a visualization of a gridded Minifocus tube’s X-ray spot taken on a production tube at Micro X-Ray, using our pinhole spot photo measurement system with no grid voltage applied. We can distinctly see two lobes in the spot. The total intensity of the spot can be determined by summing the total number of counts in the image, 1.77e7.

As we increase the electrostatic field strength with a grid voltage of -20V, we can see the two lobes are merging into one as a result of the electrostatic fields acting on the electron beam, but the spot’s sides in the X axis are still quite sloped (these slopes are often called the “wings” of the spot). Note the total counts in the spot area remain unchanged.

At -40V, the X-ray spot is now a sharp spike, with very steep sides and an intense center. Note the total count rate still remains unchanged, despite a very different shape than the spot with a 0V grid value. We are not adding X-ray flux, we’re simply focusing it in the center of the spot.

And finally, at -60V, we can see the center intensity fall slightly as the wings of the spot increase – this tells us we’ve applied too much voltage to the grid. Again, the total flux intensity remains unchanged, but over focusing the beam results in a less than optimal distribution of the available flux.

Putting It All Together

In the GIF below, we’ve animated the grid voltage changes from 0V through -65V to show the impact of grid voltage on flux distribution. The ideal grid voltage is slightly different for each X-ray tube, and Micro X-Ray will provide you with the optimal grid voltage for your tube.

So what does it mean for you, and do you need a gridded X-ray tube? As always with X-ray tubes, it depends. A gridded tube isn’t better or worse than a non-gridded Minifocus tube, it just depends what your application requirements are. Many analytical applications don’t care about the spot size at all; as long as the cone angle illuminates a larger area than the largest collimator in the system, that’s good enough for the application. However, when high flux intensity in the center of the spot is important, there’s no substitute for a well designed electron beam focusing optic. If you’re using an external polycapillary optic, this increase in flux, combined with the total power of our Seeray X-ray tube can unlock flux intensity previously reserved for sources in the kW range, allowing ultra-fast micro XRF, and even enabling benchtop XRD from a X-ray source running at under 100W!

For More Information on Gridded Tubes

If you have any questions about our gridded tubes, or any tubes at all, please reach out today!

The post Operational Tips: Do I Need a Gridded Tube? appeared first on Micro X-Ray.

This post serves as a comprehensive guide to help you connect the open-collector outputs on your Micro X-Ray integrated X-ray source to the inputs of your control components, while considering the 20mA maximum sinking current standard across Micro X-Ray integrated sources. By following these guidelines, you can ensure seamless integration and optimal performance of your integrated X-ray source. Additionally, we will explore how to connect and use a relay to drive low impedance and/or high voltage loads, expanding the capabilities of your integrated X-ray source.

Connecting Open-Collector Outputs to Your Control System

Regardless of whether your control system operates at 3.3V, 24V, or somewhere in between, the process of connecting the open-collector outputs from the integrated X-ray source is the same.

Understand Your Input Requirements

Determine the input specifications of your control system components that will receive the signals from the X-ray source module. Pay attention to the input voltage levels, any internal (built-in) pull-up resistors, and maximum current sourcing specification so you can determine if your input can be connected directly to the output, or if intermediary circuitry is required.

Identify Open-Collector Outputs

Review the X-ray source module’s documentation or datasheet to identify the available open-collector outputs and their corresponding pinouts.

Connect the Open-Collector Outputs

For circuits requiring less than 20mA and less than 24V

In the majority of cases, when feeding an open collector output into a digital input, a simple pull-up resistor is all that’s required in order to read the output, as shown in the figure below.

1. Identify the positive voltage supply (up to 24V) and ground of your control system.
2. Connect the open-collector output pin from the X-ray source module to the input pin of your control component.
3. If your control component’s input does not have a built-in pull up resistor, you’ll need to add an external one:
   1. Connect a resistor between the positive voltage supply and the input pin of your control component.
   2. Ensure that the resistor value is appropriately chosen to limit the sinking current to a maximum of 20mA. Ohm’s Law (V=IR) can be used to calculate a suitable value for R with a little rearranging to solve for R=V/I, where V is your positive voltage supply, and I is the current you wish to sink, up to 20mA.

For circuits requiring more than 20mA and/or more than 24VDC

In situations where you need to drive a low impedance load or a load with higher voltage than what can be directly handled by the open-collector outputs, a relay can be employed, as shown in the figure below.

1. Select a Suitable Relay
   1. Choose a relay that meets the specifications of your load requirements, such as the desired switching voltage, current capacity, and contact configuration.
   2. Ensure coil can be operated within the open-collector output specifications of up to 24VDC and less than 20mA sinking current.
2. Connect the Relay Coil
   1. Connect one side of the relay coil to the open-collector output pin.
   2. Connect the other side of the coil to the positive supply voltage, ensuring proper polarity.
3. Connect the Relay Contacts
   1. Connect one side of the load to the common terminal of the relay contacts.
   2. Connect the other side of the load to the appropriate contact terminal based on your desired switching behavior.
4. Power Supply Considerations
   1. Ensure that the power supply for the relay coil and the load is appropriately rated.
   2. Use a separate power supply for the load if its voltage exceeds the rating of the open-collector output.
5. Protection Measures
   1. Implement appropriate protective measures, such as diodes or snubber circuits, across the relay coil to suppress voltage spikes and protect the control circuitry.

Verify the Wiring

For either direct-driven or relay-driven operation, once the connections are made, double-check the wiring to ensure correct polarity and proper grounding. Incorrect connections can lead to malfunctioning or unreliable operation.

Signal Interpretation

In your control system software or firmware, you are now ready to interpret the X-ray source module’s open-collector outputs based on the specifications of your control components and the X-ray source manual. Design your control algorithms or logic accordingly to utilize these signals for the desired system behavior.

Conclusion

By following the steps outlined above, you can effectively connect and utilize the open-collector outputs from your integrated X-ray source module in your control system. Ensure that the sinking current at the output does not exceed the maximum specified limit of 20mA, and the voltage does not exceed 24V. With proper connections and signal processing, you can achieve seamless integration and optimal performance, enabling precise control of your X-ray source in various applications.

As always, if you have any questions about how to select or operate your X-ray source, please reach out today!

Contact Us Today!

The post Operational Tips: Using the Open-Collector Outputs on Your Integrated X-ray Source: A Guide for Low and High Impedance Inputs appeared first on Micro X-Ray.

Picking an X-ray source can be a daunting task – with all the variables and tradeoffs involved in X-ray tubes and the systems that contain them, it’s tough to know where to even begin. In today’s post, we’ll talk through the different packaged tube options available and discuss where each might fit in.

The 50kV, 50 Micron Sweet Spot

Micro X-Ray offers a range of X-ray sources that are designed to meet the diverse needs of a variety of applications. In applications where focus matters, 50kV is often a perfect voltage for our customer’s applications – high enough energy to penetrate a wide variety of common materials in various thicknesses, but low enough to make shielding a relatively straightforward affair with thin sheets of high-Z materials. A spot size around 50-100µm is another sweet spot – well focused enough to enable the high resolution images needed on modern process lines, but not so finely focused that electrostatic focusing voltages (and their complex power supplies) are required.

In the 50kV Minifocus tube category, there are several distinct product families to consider. These product families include the Minifocus Packaged Tube, the Windchill, the Aquachill, the Seeray, and the Seeray with Diamond Target. In this blog post, we’ll compare and contrast these products to help you understand which one is right for your specific application.

Because each product family contains so many options (target material, cone angle, cable lengths, etc), we won’t spend much time drilling down to particular SKUs or specific applications, but instead we’ll discuss general advantages and drawbacks of each of the product families. Once a product family or two has been identified as a good candidate for your application, reach out to Micro X-Ray and we’ll work through the rest together.

Minifocus Packaged X-ray Tube

The Minifocus Packaged X-ray Tube is an industry standard, high volume product offered by MXR. It can generally run up to 50W and has a 1W/µm power loading, with spot sizes ranging from 33µm through 250µm and a wide variety of target material choices. This product is suitable for offline applications where high resolution is important, but where shaving seconds off the measurement or exposure time isn’t the highest priority.

Actively Cooled X-ray Sources

Windchill

The Windchill is a forced air-cooled X-ray source that extends maximum power of a Minifocus Packaged X-ray tube from 50W up to 150W. It uses a small oil pump to move dielectric oil through a heat exchanger to effectively cool down the X-ray tube, enabling higher power and an extended temperature range. The Windchill has a maximum 1W/µm power loading and is suitable for applications that require higher throughput than a Minifocus tube, but where the ambient temperature is still relatively cool, such as a laboratory, or a climate controlled factory floor.

Aquachill

The Aquachill is a water-cooled X-ray source that extends the power range of an X-ray tube from 50W up to 150W. Like the Windchill, it uses an efficient oil pump to move oil through a heat exchanger to cool down the X-ray tube. The main difference between the Aquachill and the Windchill is the cooling method used for the heat exchanger. The Aquachill uses water cooling for more efficient heat removal, making it suitable for applications where the ambient temperature may be too high for forced air cooling.

Direct Anode-Cooled X-ray Sources

Seeray

The Seeray is another water-cooled X-ray source, but unlike the Aquachill which cools the tube indirectly via the oil, the Seeray incorporates direct anode water cooling for the most efficient heat removal possible in an X-ray tube. This product is useful everywhere the Aquachill is and can also provide key performance advantages in applications such as XRD and some imaging applications where focal spot drift is an issue, since the direct water-cooled anode reaches thermal equilibrium within around 5 minutes. The Seeray has a 1W/µm power loading and is suitable for applications with uncontrolled ambient operating environments where X-ray source longevity is critical.

Seeray with Diamond Target

The Seeray with Diamond Target is designed for applications where maximum brightness is required, combined with minimum spot sizes. This product is great for applications like high brightness micro XRF or single crystal XRD where high resolution and high brightness are equally important. With a 1.5W/µm power loading, the Seeray with Diamond Target provides industry-leading brightness of up to 150W in a 100µm spot size. This brightness, combined with the quick spot settling time, make it a perfect choice for coupling with X-ray optics.

Conclusion

MXR offers a range of X-ray sources that can meet the diverse needs of a variety of applications. Ultimately, selecting the right X-ray source will depend on the specific needs of your application, including resolution, throughput, and environmental conditions in your application. The team at Micro X-Ray is standing by to help assist you in selecting the right X-ray source for your application today.

The post Operational Tips: Selecting the Right X-ray Source from Micro X-Ray appeared first on Micro X-Ray.