Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Field-emission plug-and-play solution for microwave electron guns


To simplify the electron emission mechanism involved in microwave electron guns, a team of researchers has created and demonstrated a field-emission plug-and-play solution based on ultrananocrystalline diamond

On a quest to design an alternative to the two complex approaches currently used to produce electrons within microwave electron guns, a team of researchers from Euclid TechLabs and Argonne National Laboratory's Center for Nanoscale Materials have demonstrated a plug-and-play solution capable of operating in this high-electric-field environment with a high-quality electron beam.

This is an image of the electron beam produced on an Yttrium-Aluminum-Garnet (YAG) phosphor screen.

Credit: Sergey Baryshev/Euclid TechLabs

Unfamiliar with microwave electron guns? Perhaps best known within the realm of X-ray sources, microwave electron guns provide a higher current and much higher quality electron beams than conventional DC guns. Beams of this sort are also used in free-electron lasers, synchrotrons, linear colliders and wakefield accelerator schemes.

But the electron emission mechanisms involved -- laser irradiation of materials (photocathodes) and heating of materials (thermionic cathodes) -- tend to be complex, bulky or extremely expensive.

To simplify the process, as the team describes in Applied Physics Letters, they turned to a third electron emission mechanism -- field emission -- to create a plug-and-play solution based on ultrananocrystalline diamond (UNCD) originally introduced at Argonne.

Field emission "is a process of liberating electrons from solid-state materials into a vacuum by the electric field," said Sergey Baryshev, a material scientist, and Sergey Antipov, an accelerator physicist, working for Euclid TechLabs. "A strong electric field on the surface induces tunneling propagation through the surface barrier. So, essentially, our field-emission cathode (FEC) is an electron source alternative to photo or thermionic cathodes, which use an intense laser or high temperatures to liberate electrons," added Antipov.

At Argonne's Center for Nanoscale Materials, field emission properties of UNCD have been studied for several years, and researchers were able to demonstrate that UNCD performs better even in planar configurations, unlike other diamond films, which need to be shaped into high aspect ratio structures to locally enhance electric field and produce significant currents. "This is due to the unique carbon bonding configuration within the few-atoms-wide grain boundaries surrounded by nano-sized UNCD grains, which yield very high field enhancement naturally," noted Ani Sumant, a nanoscientist and UNCD specialist at Argonne.

The team's study is the first known actual testing of a planar thin UNCD film in an electron injector, in which UNCD film virtually replaces a part of an inner copper wall subject to the strong oscillating electric field. One surprise was discovering that "UNCD provides such a large charge and peak current with such low angle divergence and energy spread of the electron beam -- both of which are comparable with photocathodes," Baryshev said. "The produced electron beam is of very high quality."

Importantly, UNCD survived under harsh conditions in the microwave gun without noticeable degradation for an extended period of time. "The planar geometry of UNCD may help distribute the total electric field experienced by narrow grain boundaries--more than a trillion per square centimeter," explained Sumant.

While the UNCD FEC may one day become a true commodity electron source for conventional copper-based accelerators, the team expects to see the most interesting implications within the field of superconducting radio frequency (SRF) accelerators.

"SRF systems potentially offer higher duty cycles, which equate to higher production rates, which is important for industry," said Chunguang Jing, vice president of Euclid TechLabs. "Until now, though, SRF systems weren't considered attractive by industry because their wall-plug efficiency is low and, compared to conventional systems, mainly caused by using warm electron injectors with photocathodes (lasers) or thermionic (heaters) cathodes."

An accelerator is a complex system, and on a very basic level it's analogous to the microwave oven or kettle in your kitchen, so you can determine its wall-plug efficiency -- essentially how much consumed electricity was actually used vs. wasted.

"For SRF and conventional copper systems to produce an electron beam, this parameter is 10 percent. Its consumed energy will be 10 times greater, because 90 percent of it is wasted," noted Baryshev. "It was previously demonstrated that if SRF were fully cryogenic under liquid helium temperatures, wall-plug efficiency could be boosted to 50 to 60 percent. Our UNCD FEC may enable this option by avoiding any warm parts within an SRF system."

Why is all of this so significant? One compelling reason is that fully cryogenic high-efficiency SRF accelerators can quickly translate into huge electricity cost savings -- on the order of millions of dollars per year -- compared to electron accelerator facilities using conventional accelerators.

The team's technology is relevant to "many existing industrial and medical challenges -- including those of the highest national importance," Baryshev added.

The article, "Planar ultrananocrystalline diamond field emitter in accelerator RF electron injector: Performance metrics" by Sergey V. Baryshev, Sergey Antipov, Jiahang Shao, Chunguang Jing, Kenneth J. Pérez Quintero, Jiaqi Qiu, Wanming Liu, Wei Gai, Alexei D. Kanareykin and Anirudha V. Sumant appears in the journal Applied Physics Letters on Nobember 18, 2014. (DOI: 10.1063/1.4901723). See:


Applied Physics Letters features concise, rapid reports on significant new findings in applied physics. The journal covers new experimental and theoretical research on applications of physics phenomena related to all branches of science, engineering, and modern technology. See: 

Jason Socrates Bardi | EurekAlert!

More articles from Physics and Astronomy:

nachricht Move over, lasers: Scientists can now create holograms from neutrons, too
21.10.2016 | National Institute of Standards and Technology (NIST)

nachricht Finding the lightest superdeformed triaxial atomic nucleus
20.10.2016 | The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>