What is it about?

In this paper, we demonstrated a C-band accelerating structure (5.712GHz) In this paper we proved validity of C band accelerator (5.712 GHz) could be the sweet spot of producing extremely high electric fields and transport high amounts of current needed to develop portable accelerators. As their higher frequency counterparts can produce high field but have very small apertures meaning that they cannot transport high current. While their lower frequency counterparts can transport a high current but have very little fields meaning to gain the same energy the machine needs to be significantly larger. Thus, C band is the new sweet spot we believe to developing portable accelerators for everyday use.

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Why is it important?

Accelerators have been the backbone of many discoveries over the century and an indispensable tool for the discovery of the fundamental forces of the universe. Accelerators offer plethora of applications including medical isotopes, industrial sanitation, defense and security, targeted cancer treatments, and even creating nuclear fusion that eventually touches every human live in this planet. However, the primary concern with these machines is their gigantic size and weight. For example, the Large Hadron Collider (LHC) at CERN (The European Organization for Nuclear Research) is 26 km in circumference which means that San Francisco Bay area could fit inside the ring of the LHC. As such the construction cost of such facilities is now reaching into billions of dollars. Thus, the accelerator community has done a concerted effort over the last 20 years to develop ultra-compact accelerators that can provide the same energies of their larger counterparts keeping the footprint smaller and sometimes even portable. This is achieved by increasing the operational gradient i.e., the amount of energy gained by particles such as electrons and protons in a single meter that the accelerating structure can provide. Often it involves increasing the operating frequency of the accelerating cavities into the GHz range i.e. billions of hertz. As a rule of thumb, higher frequency requires lower footprint with an expense of high electric and magnetic fields on the surface. These fields sometimes cause arcing or breakdown of materials leaving surface deformity. This paper focus on studying breakdown behavior of cavities in C-band and a demonstration of the concept that with application of metal alloys such as Cu-Ag and with careful design, high gradients (>>100MeV/m) can be achieved. Higher frequency such as C-band allows the cavities to sustain high gradient and high surface fields with potentially zero probability of breakdowns at the surface, preventing damage to the accelerating structure. On the contrary, lower frequency structures cannot operate at such high gradients at the high-frequency counterpart since probability of breakdown and surface damage is very high. Here in this paper, we conducted an extensive breakdown study on a single cell C band structure (5.712 GHz). This band is important due to its ability to provide extremely high gradients >>100 MeV/m while allowing larger beam apertures that supports high beam current for a wide variety of applications and can also be used for proton and electron machines opening the door to this technology being widely adopted in many disciplines.


The work in this report, I believe, is the summation of my own personal research philosophy that research should always be done to help the an ordinary life. It is my opinion that research should always contribute to the enhance the fundamentals of science and in broader sense knowledge. I believe, however, research should always have its main focus on improving the lives of millions of people all around the world. and As scientists, we are here to serve the purpose of making the world a better place by helping our surroundings, communities instead of research endeavors that only serves scientific communities. We strongly believe and hope that the development of portable accelerators and its many facets to improving the everyday life can make this technology available to the corners of the world that are often forgotten by the advancements of modern technology. This research in particular its extremely close to home for me as my own father passed away when I was four years old due to a brain tumor. Where targeted radiotherapy was not available at that time where this work could make it now possible. In particular if these portable accelerators could’ve reached more rule communities that are not able to see check treatment it would’ve been extremely helpful. This would not only help developing nations but may also bring such treatments to countries in the developing world that have never received such treatments that often many people a year dying from treatments that some countries think as negligible. Then maybe someday another little boy does not have to lose his father.

Mitchell Schneider
SLAC National Accelerator laboratory

Read the Original

This page is a summary of: High gradient off-axis coupled C-band Cu and CuAg accelerating structures, Applied Physics Letters, December 2022, American Institute of Physics,
DOI: 10.1063/5.0132706.
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