The Wideroe Structure – Drift Tubes, Steel Tanks and Six Elements
Until 10 years ago the Wideroe structure was the first stage of GSIs linear accelerator UNILAC. It is named after Rolf Wideroe, a Swiss physicist, who invented the principle of radio frequency accelerator in 1928. With the help of this historic instrument the GSI Helmholtzzentrum discovered all of its six elements (107 - 112).
In the copper-coated steel tanks the 130 accelerator electrodes (drift tubes) of the Wideroe structure are connected similar to links in a chain. When the ions come out of the perforated metal cylinders, they feel the accelerating high voltage field until they enter the next cylinder. The length of each drift tube is exactly so that the high-frequency electric field always has the correct polarity, when the ions are located between the electrodes. Because of that the ions will always be "pushed" a bit forward by the field and speed up to 5% of the speed of light.