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Posts Tagged ‘srf’

This article appeared in Fermilab Today on Nov. 3, 2014.

A team from the Accelerator Division has successfully powered this small SRF cavity with a magnetron. Now they aim to power a large, application-specific model. Photo: Brian Chase, AD

A team from the Accelerator Division has successfully powered this small SRF cavity with a magnetron. Now they aim to power a large, application-specific model. Photo: Brian Chase, Fermilab

If you own a magnetron, you probably use it to cook frozen burritos. The device powers microwave ovens by converting electricity into electromagnetic radiation. But Fermilab engineers believe they’ve found an even better use. They’ve developed a new technique to use a magnetron to power a superconducting radio-frequency (SRF) cavity, potentially saving hundreds of millions of dollars in the construction and operating costs of future linear accelerators.

The technique is far from market-ready, but recent tests with Accelerator Division RF Department-developed components at the Fermilab AZero test facility have proven that the idea works. Team leaders Brian Chase and Ralph Pasquinelli have, with Fermilab’s Office of Partnerships and Technology Transfer, applied for a patent and are looking for industrial partners to help scale up the process.

Both high-energy physics and industrial applications could benefit from the development of a high-power, magnetron-based RF station. The SRF cavity power source is a major cost of accelerators, but thanks to a long manufacturing history, accelerator-scale magnetrons could be mass-produced at a fraction of the cost of klystrons and other technologies typically used to generate and control radio waves in accelerators.

“Instead of paying $10 to $15 per watt of continuous-wave RF power, we believe that we can deliver that for about $3 per watt,” Pasquinelli said.

That adds up quickly for modern projects like Fermilab’s Proton Improvement Plan II, with more than 100 cavities, or the proposed International Linear Collider, which will call for about 15,000 cavities requiring more than 3 billion watts of pulsed RF power. The magnetron design is also far more efficient than klystrons, further driving down long-term costs.

The magnetron project members are, from left: Brian Chase, Ed Cullerton, Ralph Pasquinelli and Philip Varghese. Photo: Elvin Harms, Fermilab

The magnetron project members are, from left: Brian Chase, Ed Cullerton, Ralph Pasquinelli and Philip Varghese. Photo: Elvin Harms, Fermilab

But the straightforward idea wasn’t without obstacles.

“For an accelerator, you need very precise control of the amplitude and the phase of the signal,” Chase said. That’s on the order of 0.01 percent accuracy. Magnetrons don’t normally allow this kind of control.

One solution, Chase realized, is to apply a well-known mathematical expression known as a Bessel function, developed in the 19th century for astronomical calculations. Chase repurposed the function for the magnetron’s phase modulation scheme, which allowed for a high degree of control over the signal’s amplitude. Similar possible solutions to the amplitude problem use two magnetrons, but doubling most of the hardware would mean negating potential savings.

“Our technique uses one magnetron, and we use this modulation scheme, which has been known for almost a hundred years. It’s just never been put together,” Pasquinelli said. “And we came in thinking, ‘Why didn’t anyone else think of that?'”

Chase and Pasquinelli are now working with Bob Kephart, director of the Illinois Accelerator Research Center, to find an industry partner to help them develop their idea. Inexpensive, controlled RF power is already needed in certain medical equipment, and according to Kephart, driving down the costs will allow new applications to surface, such as using accelerators to clean up flue gas or sterilizing municipal waste.

“The reason I’m not retired is that I want to build this prototype,” Pasquinelli said. “It’s a solution to a real-world problem, and it will be a lot of fun to build the first one.”

Troy Rummler

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Fermilab issued this press release today.

Alex Romanenko, sitting on the edge of a large cryogenic vessel, holds one of the superconducting RF cavities made of niobium. Photo: Fermilab (Click on image for larger version)

Alex Romanenko, a materials scientist at Fermi National Accelerator Laboratory, will receive $2.5 million from the Department of Energy’s Office of Science to expand his innovative research to develop superconducting accelerator components. These components could be applied in fields such as medicine, energy and discovery science.

Romanenko w as named a recipient of a DOE Early Career Research Program award for his research on the properties of superconducting radio-frequency cavities made of niobium metal. The prestigious award, which is given annually to the most promising researchers in the early stages of their careers, includes a $2.5 million award over five years to continue work in the specified area.

“Dr. Romanenko and his proposed research show great promise,” said Tim Hallman, associate director of the DOE’s Office of Science for Nuclear Physics. “We are pleased that he has been selected to receive an Early Career Research Program award to continue this work.”

Romanenko’s work could explain why some superconducting radio frequency cavities are highly efficient at accelerating charged particles to high speeds while others are not, as well as prescribe new ways to make cavities even more powerful. His research links t he performance of SRF cavities to the quality of the niobium metal used to make them. In particular, he investigates specific defects and impurities in niobium. Although scientists take painstaking measures to ensure that the niobium is completely pure and that the final SRF cavities are free from any contaminants, dust or debris, the cavities do not always perform the way that they should. Romanenko’s research is dedicated to finding out why that happens.

Romanenko began his research on SRF cavities as a graduate student at Cornell University, an institution known for its SRF research. He continued his award-winning work at Fermilab when he joined the laboratory in 2009 as a Peoples Fellow, a prestigious position given to scientists who have the potential to be leaders in their field. (More information at
http://www.fnal.gov/pub/today/archive_2011/today11-03-02.html )

Through his research, Romanenko found that a new, previously unexplored, type of defect near the cavity surface may result in surface differences that are responsible for a cavity’s inferior performance. What he found was surprising: the defect sites often contained niobium-hydrogen compounds, which might form when the cavities are prepared for operation. Specifically, he was able to pinpoint the problematic area to the first 40 nanometers of a cavity’s surface, a thickness equivalent to 120 layers of niobium atoms.  

“The technology of these cavities has developed so fast recently that it is ahead of the corresponding science,” Romanenko explained. “We know how to make them work to a certain level of performanc e, but do not necessarily understand the full physics behind why they do so. I hope to understand why cavities behave in certain ways first, improve on this and then apply what I learn to other materials.”

If Romanenko can isolate the specific nanostructural effects that cause problems in cavities, then Lance Cooley, Romanenko’s supervisor and head of the new Superconducting Materials Department in Fermilab’s Technical Division, is prepared to direct other scientists to develop ways to prevent or control them and transfer that knowledge to industry. This could someday make it possible to mass-produce nearly perfect niobium cavities as well as lay the groundwork for cavities made from other superconducting materials that can perform at higher temperatures and accelerating fields. Such high-performance cavities—strung together to create powerful, intense particle beams—would lead to accelerators that can be used in indust ry, in hospitals and at research institutions. These accelerators are needed, for example, to produce a range of radioisotopes for medical diagnostics and have the potential to treat nuclear waste, among other applications. (More information at http://www.acceleratorsamerica.org/applications/index.html)

Strung together like the pearls of a necklace and cooled to ultralow temperatures, SRF cavities can accelerate particles with high efficiency. Photo: Fermilab (Click on image for larger version)

“This award recognizes the high caliber of research that takes place at Fermilab,” Cooley said. “It is because of the laboratory’s existing world-class research program that Alex’s research is likely to succeed.”

The monetary award will cover part of Romanenko’s research efforts, fund a postdoctoral associate and a part-time technician, and pay for advanced analysis techniques used to examine surfaces in the next five years.

Fermilab is a national laboratory supported by the Office of Science of the U.S. Department of Energy, operated under contract by Fermi Research Alliance, LLC.

The DOE Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit http://science.energy.gov

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This article appeared in ILC Newsline July 28.

Editor’s note: Fermilab has been working with national and international institutions to develop superconducting radio-frequency cavities and their encapsulating cryomodules for next-generation accelerators, including the proposed International Linear Collider and the proposed Project X.

CM1 with its recently installed RF distribution system ready for testing. Image: Jerry Leibfritz

SRF technology enables the acceleration of intense beams of particles to high energies more efficiently and at lower costs than other technologies. SRF technology could also be applied in the areas of clean nuclear energy and transmutation of radioactive waste.

Cryomodule 1 is now firing on all eight cavities.

Cryomodule 1, Fermilab’s test cryomodule for ILC-type accelerating cavities and superconducting radiofrequency (SRF) technology, was powered up as a complete, multi-cavity instrument earlier this month. Previously, researchers had delivered power only to the individual cavities inside it.

“We’ve operated superconducting cavities before, but this is the next step in scale,” said Sergei Nagaitsev of Fermilab’s Accelerator Division. “Operating a single cavity in its own cryostat is comparable, but with a full cryomodule, the complexity goes up by an order of magnitude.”

Since the cool-down of CM1 last November, scientists and engineers have been busy installing the plumbing for power distribution, called waveguides; upgrading the water skid, which helps with the cooling of the high-power RF equipment; and taking data on each cavity’s accelerating gradient and quality factor, or Q. Researchers completed the cavity tests in June.

“The big question now is how this module performs compared to when the cavities were at DESY,” said Fermilab’s Elvin Harms. The German physics lab DESY provided all eight CM1 cavities, which were tested before they came across the Atlantic. Over the coming weeks, researchers will continue to feed power into cryomodule to gather data on how cavities perform as a single unit rather than as individual elements. The hope is that their gradients and Q will be in reasonable agreement with DESY’s numbers.

To make sure the data that comes through is reliable, the CM1 team will work on calibrations, test RF power operation, and work the kinks out of the system. Then comes a multi-week programme where scientists will perform stability tests and beam studies for the ILC beam current programme, which includes tests that can be conducted without the presence of beam. Researchers will also use CM1 for tests for Project X, Fermilab’s proposed proton accelerator programme.

Not all sailing was smooth in the time since the November cool-down. Some cavities still have wrinkles that need to be ironed out.

“Nevertheless, the fact that the integration of it all into a single system worked is a tremendous boost for the Accelerator Division, the Technical Division and our collaborators,” Nagaitsev said.

Collaborators on CM1 include researchers from DESY, INFN in Italy and KEK in Japan.

“Many people have invested a lot of time in CM1,” Harms said. “They’ve been eagerly waiting to get this to this day.”

– Leah Hesla

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Superconducting in West Bengal

Friday, March 4th, 2011

–by Nigel S. Lockyer, Director

[Ed. Note: This is the second of a three-part series penned by Nigel on his trip to India in early March 2011.]

Day 1 (Feb 27, 2011, in some time zone): Had dinner this evening with a postdoc and friend from TRIUMF, Smarajit, who has just joined the faculty at Delhi University (a small school…only 390,000 students!) as an assistant professor. I experienced golgappas. Basically it is an appetizer made of a crispy wafer in the shape of a hollowed-out pumpkin filled with spicy water. You put the whole thing in your mouth and let the flavours explode was my instruction from Smarajit. It exploded all right, my throat was on fire for 30 seconds making me speechless. Then Smarajit became concerned that I shouldn’t have drank it because the water may have come from the local tap. We asked the waiter and it did come from the tap. Oh well…too late now. Of course I went back for more. It was an experience worth repeating. Over dinner, we discussed the research trajectory his career might take over the next few years. I told him he has to first understand the funding system in India, make research connections in his department and university, with colleagues and labs in India and then finally internationally. Needless to say, for Smarjit, the international component would be the easiest because he has many connections around the world and established collaborations. The Indian University Accelerator Centre” (IUAC) is an ideal place to do experiments with stable beams because it is world class and is located in Delhi…very convenient. IUAC may be the most advanced institute in India for superconducting radio frequency accelerator research…the same area TRIUMF has focused on for accelerator development.

Got up at 3:00 AM and headed to Delhi’s brand new beautiful and very large airport (opened July 2010 for the Commonwealth Games) on a new highway for the trip to Kolkata. Oh did I mention the automobile horn is undergoing phase-I trials in India….every car is expected to test out their horn essentially all the time.

Day 2: Big news today is that England and India tie in a nail biter played in Bangalore. The game of cricket, brought to India by the “Britishers” (that is what the Indians call the British) is a game the Indians are crazy about, just like Canadians and ice hockey. The world cup game is a little like baseball, wooden bat, flat rather than round, big grass field in a large stadium, a batter and a pitcher or as they say bowler. No hot dogs but lots of dahl. Not sure about beer sales in the stadium but Indians like beer (and scotch). Fans do paint their faces and are “engaged” in the game like everywhere else. In cricket there are fixed number of pitches for each side. Called “Overs,” or six legal pitches, they play each for 50 Overs or 300 pitches. To score you must hit the ball and be able to run between the wickets. There are two wickets, 20 feet apart, two batters, one end to be bowled to at any given time. One team bats, 11 players each side, roughly half are bowlers. The games big name, an Indian named Sachin Tendulkar (“Cricket is my religion and Sachin is my god,” they say), is called the master blaster. No more need be said. This year Australia has a good team, India, and Sri Lanka. One high point for me was that Canada had a team in the world cup. I did not know that. When Canada played Zimbabwe, the Indian newspaper Hindustantimes called it the battle of the “minnows.” That’s not good for sure. Perhaps if they used cricket bats instead of than hockey sticks they would do better.

After a hair raising “yikes” ride from the airport, (I’ll never complain about Vancouver traffic again) to the Kolkata Variable Energy Cyclotron Centre (VECC) we checked into our rooms at the new dorm. My first thought was how many people are killed in India in car accidents. They said not too many but it came out later the number is 85,000 per year, or eight times the US, which is also high especially when you take into account the relative number of drivers. More people in India but not that many drive as much as in the US!

We pretty much started our collaboration meeting upon arrival. The meeting started with the Director of VECC, Rakesh Bhandari, welcoming us and then presenting the plans for his laboratory. I followed with the status and plans for TRIUMF. Both teams made interwoven presentations all day focused on the VECC test as we now call it. This is the 30kW electron beam test we must complete together (according to our MOU) by March 2012…a tight schedule. It will include a 300 keV electron gun, a low energy beam transport and de-buncher, and an accelerating section called the injector cryomodule or ICM. We are building two such modules together…referred to as ICM1 and ICM2…one stays at TRIUMF after the test and one is shipped to India. Then we got started with detailed presentations by Lia Merminga, Head of TRIUMF’s Accelerator Division, Bob Laxdal, Head of our SRF Department and co-Deputy Division Head , and Amiya Mitra, Head of our RF group (Amiya is originally from Bengal). The room was full (~25 people) of young Indian physicists and engineers, a good mix of men and women…lots of questions and interest from them.

VECC is planning a major new isotope facility, called ANURIB, which stands for “A National Facility for Unstable Rare Isotope Beams.” The young researchers and engineers are getting intellectually engaged in the scientific and technical design challenges of the planned project. Interestingly, we learned that VECC is expanding to a new “green field” site called Raharjat in a few years which allows them to grow their present rare isotope beam facility. There were numerous hot tea and cookie breaks through the day…to keep us awake….jet lag had set in already. The TRIUMF/VECC collaboration works well because we have similar goals but neither lab individually has the resources to do what they wish to do… so pooling our resources makes a lot of sense.

VECC presently uses its room-temperature cyclotron (they have just commissioned a superconducting cyclotron as well) to accelerate protons (or alphas) and then send them to strike a thick target that then produces various unstable nuclei. They do experiments with materials as well as nuclear physics. After the target they have a few acceleration stages that increases the beam energy up to 1.2 MeV per nucleon. Their plan is to reach 2.0 MeV per nucleon. They wish to do this by collaborating with TRIUMF on a superconducting radio frequency (SRF) technology heavy ion linear accelerator, an area of expertise of TRIUMF.

At the end of the day we went for dinner is a restaurant downtown…about 15 people. It was a pleasant evening, food was great, beer was better, and the discussion moved in and out of physics and life in India. Surprisingingisinginglyly (southern India spelling of surprising), there was only one other vegetarian besides myself. Statistically, about 40% of Indians are vegetarian. What’s with the scientists?… or maybe Bengalis? The director’s wife joined us later. She is a school teacher and she taught English and Hindi to grade 11 and 12 students…basically two official languages, although as we gathered fairly quickly, the Bengalis have their own language, use it and wish to keep it…. sound familiar? She was late grading papers from an exam earlier in the day and needed to finish and post grades. She described her students as serious students, over 80 in one class, 60 in another, and she enjoyed her job. They better be serious with that many high school kids in a class. I was exhausted after my first day, happy with the progress and happy to hit the hay that evening.

Day 3:  Feeling good…. more like a person after a good night’s sleep. Walked around the site with Bob Laxdal to make sure we understood each other on various priorities for the VECC test. The site is about 12 acres in size surrounded by either a fence or brick walls. VECC is in a residential area, with houses across the street, cars honking and people walking or cycling by all the time. Bob is the lead scientist for the test and is responsible for the schedule.

The day started off in the Director’s meeting room where we discussed further our plans for collaboration. It is the Year of India in Canada and we discussed having some kind of collaboration event later in the year in Canada. That would be nice. Our MOU requires us to meet once per year in each location and review progress. This is a way of making sure each side delivers what it agreed to do. In general, we are a little behind schedule and so we spent time discussing how to catch up before one of the “major milestones” March 2012, when we planned a joint beam test at TRIUMF which we refer to as the VECC test.

We then went to the conference room and the final presentations were made. In the late afternoon we drove out to the new 25 acre green field site near the airport with chief civil engineer and saw the first evidence of power being brought onto the site. Occupancy is still a few years away. Bob headed off to the airport and the rest of us went to dinner downtown. We discussed the VECC plan to add the first accelerating cryomodule (ACM1) after the ICM only after moving to the green field site. This means the tests at VECC will be limited to about 25 MeV….they seem happy with that.

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