The invention relates generally to a method and apparatus for generating coherent near millimeter wavelength radiation. More particularly, the invention relates to a diffraction radiation generator having a depressed collector, in which elements used to decelerate the electrons in the ribbon electron bean can also be used to analyze the ribbon beam.
In a diffraction radiation generator, such as an orotron, a ribbon electron beam is generated by applying a voltage between the cathode and anode of an electron gun. Generally, the anode is grounded and a negative voltage is applied to the cathode. The ribbon electron beam is directed across a slow wave structure within an open resonator to a collector disposed on the opposite side of the open resonator from the electron gun. In an orotron, theSFGate: Day in Pictures

April 27, 2012 9:19 AM

Photo: Philipp Guelland, Associated Press

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The few weeks old Asian elephant bull (Elephas maximus) Assam plays in the sand during the first appearance in the outdoor enclosure at the Hagenbeck zoo in Hamburg, northern Germany, Friday, April 27, 2012. (AP Photo/dapd, Philipp Guelland) less

The few weeks old Asian elephant bull (Elephas maximus) Assam plays in the sand during the first appearance in the outdoor enclosure at the Hagenbeck zoo in Hamburg, northern Germany, Friday, April 27, 2012. ... more

Asian elephants take a bath in a pool at the zoo in Hanover, northern Germany, on April 27, 2012. Five baby elephants are raised in the zoo Hanover. AFP PHOTO / HOLGER HOLLEMANNHOLGER HOLLEMANN/AFP/GettyImages

Asian elephants take a bath in a