Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

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

19.11.2014

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: http://scitation.aip.org/content/aip/journal/apl/105/20/10.1063/1.4901723

ABOUT THE JOURNAL

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: http://apl.aip.org 

Jason Socrates Bardi | EurekAlert!

More articles from Physics and Astronomy:

nachricht Measured for the first time: Direction of light waves changed by quantum effect
24.05.2017 | Vienna University of Technology

nachricht Physicists discover mechanism behind granular capillary effect
24.05.2017 | University of Cologne

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: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

Im Focus: Using graphene to create quantum bits

In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.

In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

Physicists discover mechanism behind granular capillary effect

24.05.2017 | Physics and Astronomy

Measured for the first time: Direction of light waves changed by quantum effect

24.05.2017 | Physics and Astronomy

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>