A new detector system with high time resolution ͑1 ms͒ has been developed and applied for the continuous measurement of spectra in the vacuum ultraviolet ͑VUV͒ and extreme ultraviolet ͑EUV͒ wavelength region at the fusion plasma experiment Torus Experiment for Technology-Oriented Research ͑TEXTOR͒. The system consists of an open multichannel-plate ͑MCP͒ detector with subsequent first generation ͑Gen I͒ light amplifier and a camera head which is based on a linear photodiode array with 1024 elements ͑pixels͒. The camera head provides the output signals of the individual pixels sequentially as an analog voltage with a full spectra rate of 1000 per second, which are measured using a PC-based data acquisition system. Three vacuum spectrometers operating in the VUV/EUV region ͑10-130 nm͒ have been equipped with the new system and a successful campaign of measurements from about 4000 discharges at TEXTOR has been performed. Spectra are recorded with a usable linear dynamic range of 10 bit and a wavelength resolution corresponding to a width of 3-4 pixels. © 2004 American Institute of Physics. ͓DOI: 10.1063/1.1763261͔In magnetically confined fusion plasmas a detailed monitoring of the impurity content is frequently performed using broadband spectrometers in the vacuum ultraviolet ͑VUV͒ and extreme ultraviolet wavelength range. [1][2][3][4][5] Operating these spectrometers at high time resolution, the radial transport properties of plasma impurities can be studied by means of transient impurity injection experiments, where the time evolution of spectral lines from different ionization stages is used to observe the radial propagation of impurity particles from the cold plasma edge towards the hot plasma center. 2,6 -11 In the case of medium-sized fusion experiments like the tokamak TEXTOR, an accurate analysis of such transient experiments requires a time resolution on the order of 1 ms, since the typical radial particle transport times are in the range of only 5-30 ms. 11 In this Note we present the design of a detector system based on the Hamamatsu C3904-F linear array which allows to continuously record spectra in the VUV/EUV wavelength range at a full spectra rate of 1000 per second.The schematics of the detector setup is shown in Fig. 1. An open MCP detector with 40 mm diameter converts the VUV photons to visible light. The single-stage MCP with high quantum efficiency ͑CsJ coating͒, high amplification of up to 10 4 ͑L/D ratio of 60/1͒ and extended dynamic range allows for linear operation up to maximum output current densities of about j output ϭ0.5 A/cm 2 , while a fast P46 phosphor ensures high time resolution ͑decay time below 1 s͒. In order to further increase the detector output light intensity above the level defined by the saturation threshold of the MCP, a proximity-focused first generation ͑Gen I͒ light amplifier ͑by Proxitronic͒ is used, providing an additional amplification factor of 10. Including all amplification and efficiency factors as well as the transmission losses in the detector setup, an indivi...

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Dichroic filters have been used to shield effectively the far infrared (FIR) detectors at the interferometer/polarimeter on TEXTOR. The filters consist of metal foils with regular holes, the hole diameter, the mutual spacing and the thickness of the foils are chosen to transmit radiation at the design frequency with transmission >90%. The attenuation at the low frequency end of the bandpass filter is about 30 dB per octave, the high frequency transmission is between 20% and 40%. The filters have been used to block the stray radiation from the megawatt microwave heating beam to the detectors of the FIR interferometer, operating with power on the detector in the milliwatt range. If required, the low frequency attenuation can be still enhanced, without compromising the transmission in the passband. The FIR interferometer used for plasma density and position control is no longer disturbed by electromagnetic waves used for plasma heating.

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