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BE: Beschleunigerphysik
BE 4: Diagnostics and Instrumentation II
BE 4.4: Vortrag
Dienstag, 1. April 2014, 10:30–10:45, ZEU 255
Laser-induced fluorescence as neutral gas density diagnostic for an hybrid plasma accelerator — •Johannes Wein1, Constantin Aniculaesei1, Gregor Fuhs1, Oliver Karger1, and Bernhard Hidding1,2 — 1Universität Hamburg, Germany — 2University of Strathclyde, Glasgow, United Kingdom
Relativistic electron beams with small emittance and size are needed for advanced applications such as free electron lasers (FEL) and other coherent light sources in the x-ray regime. The concept of underdense plasma photocathode acceleration uses a beam-driven plasma wave in a two component gas mixture consisting of a low ionisation threshold medium (LIT) a high ionisation threshold medium (HIT) and a low-energy laser pulse. Electron bunches with sub-fs-length and unprecedented normalized emittance down to 10−9 m rad can be produced. To achieve a controlled injection a homogenous plasma density is very important. Therefore a plasma oven for rubidium as both HIT and LIT medium is developed. The presentation discusses laser-induced fluorescence (LIF) as a method to measure the neutral gas density profile in this oven. LIF is a widely used technique for the detection of atomic species in gaseous environments. It excites present atoms with a laser and measures the intensity of transversally emitted relaxation photons. This method is capable to measure the gas density with high accuracy over a wide range of values.