New Terahertz Plasma Diagnostic System for Nuclear Fusion Reactors

By Will Soutter

http://www.azom.com/news.aspx?newsID=42606

Engineers at Lancaster University are reinventing the vacuum tube to produce Terahertz signals to monitor plasma turbulence in nuclear fusion reactors.

The Engineering and Physical Sciences Research Council (EPSRC) has provided £450,000 for the study, which is being done by a collaborative group including researchers from the University of Leeds, the Beijing Vacuum Electronics Research Institute and the University of California Davis.

 “The device developed by this project will result in a novel plasma diagnostic system which is fundamental for the future development of nuclear fusion reactors, potentially leading to a breakthrough in nuclear fusion techniques."

Professor Claudio Paoloni   

Nuclear fusion is one of the cleanest forms of energy possible, and it could provide an almost inexhaustible supply of energy. However, getting practical fusion reactor running is extremely difficult to achieve. It requires temperatures exceeding 100 million °C for the fusion reaction to take place, and a strong magnetic field to contain the fusion plasma.

During the fusion reaction, unwanted turbulence may take place, which could disrupt the plasma enough to slow the reaction or prevent it taking place altogether - leading to a loss of energy, or even hazardous containment issues.

Terahertz vision

Terahertz waves possess specific properties which enable them to non-destructively penetrate different types of materials. They hold promise for use in practical nuclear fusion reactions, as terahertz radiation can help understand plasma behavior without greatly disturbing the delicate fusion material.

Previously, research into the applications of terahertz radiation has covered detection of explosives, analysis and restoration of artistic masterpieces, and diagnosis of cancer. The technology has been limited to laboratories, however, as the techniques used require powerful terahertz sources, which are typically very large in size.

The old and the new

The team of researchers intends to develop a powerful, compact and cost-effective powerful Terahertz vacuum electron device by using the latest microfabrication processes to allow traditional vacuum tubes to reach terahertz frequencies.

The device being built would be installed at the nuclear fusion test facility in Princeton (the National Spherical Torus Experiment) and would become the main part of the plasma diagnostic system. The new device would enable commercialization of the technology by taking it from the laboratory to the market.