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You are here: MEDICA Portal. Our Topics in 2009. Topic of the Month October: Laser Medicine. Cancer.

Miniature Source Using Wiggling Electrons

Miniature Source Using Wiggling Electrons

Photo: Laserlight

Physicists at Munich's Cluster of Excellence "Munich Centre for Advanced Photonics" (MAP) of Ludwig Maximilian's University of Munich and Max Planck Institute of Quantum Optics (MPQ) in Garching are the first to succeed on the laboratory scale in producing soft X-ray radiation by means of laser light.

A team around Prof. Florian Grüner and Prof. Stefan Karsch now aims to provide brilliant X-ray radiation inexpensively in a compact device. By means of intense laser light and a plasma of ionized hydrogen atoms, they produced soft X-ray radiation with a wavelength of about 18 nanometres.

For this purpose the physicists used laser pulses lasting just a few femtoseconds, a femtosecond being a millionth of a billionth of a second. On this ultrashort time scales, the light pulses reach powers of about 40 terawatts; for comparison, an atomic power plant generates powers of about 1000 megawatts, which is 40,000 times less.

The enormous powers of the pulses are only made possible by their extreme shortness. The strong electric and magnetic fields of the light pulses separate electrons from hydrogen atoms and thus produce a plasma. These electrons are accelerated with the same laser pulse to almost the speed of light within a distance of only 15 mm, which is more than a thousand times shorter than that needed by conventional technologies used to date.

The electrons then enter an undulator, a device 30 centimetres long and 5 centimetres wide. It produces magnetic fields that force the electrons to take an undulating sinusoidal path, which transversely accelerates the electrons, causing them to emit photons in the soft X-ray range. So far, only light in the visible to infrared ranges, i.e. with much longer wavelengths than that of X-radiation has been shown with similar methods.

The radiation can likewise be applied in, for example, medicine to detect minute tumours before they can spread. This would greatly enhance the chances of curing cancer patients.; Source: Munich-Centre for Advanced Photonics (MAP)


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