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Stanford, Varian to develop new microwave power source

STANFORD -- The Stanford Linear Accelerator Center (SLAC) and Varian Associates Inc. have signed a $1.5 million cooperative research and development agreement to design, engineer and test advanced microwave tubes called klystrons to power the center's new B Factory.

Klystrons are important sources of power for particle accelerators used in physics research, radiation therapy and semiconductor manufacturing. They were invented in the late 1930s by Russell and Sigurd Varian, who founded Varian Associates in 1948 to commercialize such devices. In recent years, however, European and Japanese companies have captured the lion's share of the market for high- power klystrons needed for particle physics applications.

Under the terms of the agreement, SLAC and Varian will combine resources to develop and test two different designs for a high- power klystron, one of which will then be selected for use in the B Factory. Varian will explore the possible use of these klystrons for other emerging commercial and industrial applications, such as microwave process heating and industrial accelerators.

The Cooperative Research and Development Agreement, known as a CRADA, provides a means to transfer advanced technologies from U.S. national laboratories to private industry. SLAC's sponsoring agency, the Department of Energy, authorized the use of this type of agreement, under which its laboratories share project costs with industrial partners. Several U.S. manufacturers were invited to collaborate on the klystron design project, and Varian accepted.

In an Oct. 4 press conference held in San Francisco, President Clinton announced Secretary of Energy Hazel O'Leary's decision to award the B Factory project to SLAC. Also known as PEP II, this facility will be an upgrade of the Positron Electron Project, an existing particle collider housed in a 2.2 kilometer tunnel. It will produce millions of short-lived subatomic particles called B mesons.

By precisely measuring how B mesons disintegrate, scientists hope to learn more about the differences between matter and antimatter. Of fundamental importance to particle physics and cosmology, this research has far-reaching implications for understanding the origins of matter in the universe.

In particle accelerators, klystrons generate a very high- frequency electric field (one that reverses direction many millions of times per second). This microwave field boosts charged particles to high speeds and energies. Engineers refer to klystrons as "tubes" because the microwave-generating section of the device is a cylinder operating under a vacuum, like a vacuum tube.

The B Factory requires a 1200 kilowatt klystron that can operate continuously at a frequency of 476 megahertz (476 million cycles per second). It will be the most powerful klystron of its class. The prototype designs will be based on technology similar to a 500 kilowatt klystron that SLAC recently built and successfully tested. One of the 1200 kilowatt prototype designs will use standard technology, and the other will incorporate advanced technologies developed by Varian.

"Collaboration with Varian makes good sense because we can work closely together to include manufacturing and operational efficiencies in the design process," said SLAC Project Manager Robert Phillips. "Varian's participation can provide alternative technologies, with which SLAC has limited experience, to better optimize the klystron."

"This agreement will lead to the introduction of a new tube that should give Varian entry into key existing and emerging markets," said Armand Staprans, vice president and general manager, Varian Microwave Power Tube Products. "By participating in the initial design, we will be able to influence the manufacturability and specifications of a tube that will more closely meet many of our customers' requirements."

Among potential applications of this klystron are devices and equipment for cancer therapy, transmuting radioactive waste, lithography in microchip processing, and producing specialized semiconductors and medicines using ion implantation.

The Stanford Linear Accelerator Center is a national laboratory devoted to research in high-energy physics and the use of synchrotron radiation in science and industry. Located about 30 miles south of San Francisco, California, it is operated for the Department of Energy by Stanford University.

Varian Associates, Inc., is a diversified international high- technology company with annual sales in excess of $1 billion. Headquartered in Palo Alto, California, it produces equipment and components for medical, communications, scientific, industrial and defense markets worldwide.



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