Manufacturing Techniques of a Linear Accelerator (LINAC)

By:  Samy Hanna, PhD, PE. - Consultant Precise operations of medical and industrial linear accelerators impose certain demands on both materials used and fabrication techniques utilized. They both need to be compatible with ultra-high vacuum, high-power RF, and the presence of particle beams. In this Linear Accelerator Blog Post, I will briefly discuss materials compatible with these demands an...
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STRINGERS & PIPES

Recall the blistering or ruptures that can be experienced when you braze non-OFE Copper in Hydrogen (see Blog Post October 7, 2009).  As a follow-up post, we want to briefly discuss “stringers.”  Stringers are actual holes or leaks paths in the material that follow grain directions and are intrinsic to many grades of materials that are used in vacuum applications.  (more…)
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Reading Phase Diagrams

Back in September 2009 we published a Post titled, “Wetting, Braze Flow and Filler Spreading,” and for those of you who were left hanging, here is our new Post on using phase diagrams to understand Spreading. Why do we experience excessive spreading with some filler (braze alloys)/substrate interactions and poor spreading in others? Let’s examine phase diagrams to explain the following observatio...
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Brazing Ceramic to Metal

Metallization vs. Active Alloy Brazing Applications for brazing ceramic to metal are most commonly found in microwave tube, semiconductor feedthru and laser devices, where high vacuum integrity and dielectrical properties are required. More recently, medical and military devices have brought forward new demands for ceramic to metal seals, which require biocompatibility and high joint strengt...
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How to read a Phase Diagram and Why You Might Want to.

Phase diagrams are a great tool for the Brazing Engineer. While its is certainly true that most brazing applications involve systems more complicated than a binary alloy represented by the common phase diagram, nevertheless, the binary phase diagram is an invaluable tool both for answering questions about why a particular braze alloy and substrate interact the way they do and it can also help to p...
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Brazing Copper in Hydrogen Gas

Hydrogen Brazing Here at Altair Technologies most of our products are for high vacuum applications and we therefore do most of our brazing in Hydrogen Gas or in a high vacuum atmosphere. During the braze run, while assemblies are being heated up to braze temperature, the furnace “bell” sees a steady flow of Hydrogen gas. This process continues until parts are below a certain temperature at which t...
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Advantages of Brazing and Fabricating Complex Geometries

When fabricating complex geometries, whether it’s by die casting, e-beam welding, or 5- axis machining, there can be distinct advantages when brazing is used as a means of creating the final assembly.  Manufacturing of cavity structures utilizing standard brazing principles, for example, is becoming a current trend.   Structures with internal cavities are used in many applications including RF p...
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Wetting, Braze Flow and Filler Spreading

The term “wetting” is commonly used to describe the flow of braze alloy or braze filler across a surface. However, before we get more into wetting, let’s recap the brazing process: First, two components are placed very close to or in contact with each other and a braze filler metal is placed in contact with BOTH parts. The filler and components are heated to just past the melting temperature of th...
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The Advantages of Laser Welding For Brazing

Laser Beam Welding (LBW) is a high energy welding process that continues to expand into modern industries and new applications because of its many advantages.  Some of the advantages of laser welding versus arc-welding are: High power density: deep weld penetration with minimal Heat Affected Zone (HAZ) Automation: easily automated using robotic machinery or CNC Accessibility: non-contact nat...
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Brazing Aplications Above 1000 C

Most of the brazing we do at Altair Technologies occurs between 800° C – 1270° C. Finding a suitable braze-alloy or “filler” to melt in this temperature range is not difficult. However finding a braze alloy, or even base materials, that will withstand operation over 1000° C can be tricky. One of the first questions to ask is what is the operating atmosphere or environment (high vacuum, air or?) an...
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