Instrumentation

Pulsed and CW Lasers:

A number of He-Ne continuous lasers are available (power range from 1 to 35mW). Four continuous Argon lasers, with power up to 5W, are also available for visualisations, Laser Doppler Velocimetry, Rainbow Interferometry, Particle Image Velocimetry and Doppler Global Velocimetry. Three Nd-YAG lasers, for Particle Image Velocimetry, producing double pulses of 5 ns duration with spacing as low as 200ns, at repetition frequency of 10Hz and output energy ranging between 150 and 400mJoule. One of these lasers is a mini-YAG that can emit in the UV range as well as in the visible range. A second mini-YAG ig is part of a micro-PIV system.

Laser Doppler Velocimetry:

Five complete optical systems for LDV measurements are available: three modular multipurpose systems, a TSI two-component dual color backscatter system, and two phase Doppler analysers (PDA) measuring particle size (from 1mm to 10mm) and velocity. Various accessories such as Bragg cells or beam expanders may be added to the modular optics. Five period counters are available for the Doppler signal processing. One of these accepts Doppler frequencies up to 200MHz, and the four others operate in a range of 10kHz to 20MHz. The PDA has a range of 1kHz to 30MHz. The TSI LDV is equipped with an IFA processor working in the frequency domain. Several traversing tables are available for use with these LDV systems. Four of them are motorised and allow displacements along three axes. Among these, a traversing table is fully computer-controlled. Airflow seeding systems include four oil-smoke generators together with a pressurized Laskin's nozzle system and several atomizers for aerosol generation.

Particle Image Velocimetry:

Over the past twenty years a large number of developments in this domain have been made at the VKI. Several home-made systems are available. The three Nd-Yag pulsed lasers described above are available for PIV. A complete TSI system is available with a RS 170 camera (640x480 pixels), a laser synchronizer, a host computer and the INSIGHT software for PIV processing. Two PCO cameras are used for PIV. They have a resolution of 1280X1024, a 12-bit output and are capable of a time interval of 200ns between the grabbing of the two images. Each camera is associated with a frame grabber installed on a PC computer. The two PCO cameras can be combined for stereoscopic measurements. PIV processing is mostly performed using the VKI-developed software WIDIM, but another processing technique also developed at VKI, the Particle Tracking Velocimetry or PTV is also available for multiphase flows. A micro-PIV system that include a mini-YAG laser connected to a microscope through a fiber optics and a PIV camera is also available. It is used to measure single or two-phase flows in channels ranging from 25 micrometer to 2mm.

Hot Wire Anemometers:

More than 20 VKI-designed and constructed systems are available, some including a linearizer, and some without, but with a signal conditioning filter/amplifier for data acquisiton. A commercial state-of-the-art 4-channel hot wire anemometry system was very recently purchased.

Microcomputers/Acquisition:

More than 20 PC's equipped with multi channel analog and digital interface boards, with 12 to 14bit resolution and acquisition frequencies ranging from 4 KHz to 1MHz. A 96 channel, multiplexed, 100KHz A/D 12 bit converter, PC based data acquisition system is available for the Plasmatron. Four 8-channel, 1MHz systems are available in the TU department.

Transient Recorders:

Two 32-channel non-multiplexed systems are available for the Longshot facility which may be used individually or in tandem; controlled by a PC; 50kHz sampling rate per channel. Three additional systems for the CT2/CT3 lab, also PC-controlled, have respectively a channel capacity, max sampling frequency and memory depth per channel of: 64 channels at 300kHz/ch and 64k; 8 channels at 1MHz/ch and 256k; 48 channels at 50kHz/ch and 128k.

Infrared radiometer system:

2 infrared cameras, operating in the 8 to 12µm and in the 8 to 9 µm wavelength range, for remote, non-intrusive surface temperature mapping.

Optical pressure measurements:

A UV light source, optical bench and calibration set-up for pressure sensitive paints. Compact UV light sources are also available for installation in facilities. Improved paints and a 12-bit video camera are also available.

Image Acquisition and Processing:

A number of video cameras, recorders and PC video acquistion/processing boards are available for use in optical/visualization experiments.  A high speed camera with variable framing rate up to 150 kHz is also available for recording of transient phenomena.

Emission Spectrometer System:

A spectrograph with a focal length of 1m equipped with 2 gratings (1200 gr/mm with spectral range 400-1200nm and 3600gr/mm with spectral range 150-450nm) and with a LN2-cooled array of CCD detectors (800 x 2000 pixels) is available for the Plasma Facilities. Commercial software allows performing data acquisition and part of the processing on line. 
A new compact, fast-sample spectrometer that covers the spectral range from 200 to 900nm provides complementary capability for temporally resolved measurements at lower spectral resolution.  Two new compact, fast-sample spectrometers that cover the spectral range from 200 to 900nm provide complementary capability for temporally resolved measurements at lower spectral resolution.

Laser Spectroscopy Optical Laboratory:

A third Nd:YAG laser is used to pump a high spectral resolution, tunable dye laser for spectroscopic experiments.  This laser is also equipped with frequency tripling to obtain UV radiation for single-photon excitation of molecular species and multi-photon excitation of atomic species. Dedicated instrumentation includes fast digital oscilloscopes and a multi-channel, gated integrator detection system and a small flow reactor for calibration of fluorescence signals to allow absolute species concentration measurements.

 
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VKI, CENTER OF EXCELLENCE

ESA          LEDITH