Schematic of the VINETA experiment with the positioning system for wave detection.
Frequency response of the tested Hall sensor, the magneto-resistive sensor, and the sensor with low noise amplifier. In (a) the frequency-resolved sensitivity of the devices is shown, in (b) the signal-to-noise ratio. The highlighted frequency range indicates the intended operation regime of the probe in VINETA from 1–100 kHz.
Filter and attenuation network for connecting one detection coil to the low-noise amplifier.
Measured transfer function in terms of (a) amplitude and (b) phase of the rf-protection input filter without amplifier.
Electrostatic pickup measurement of the -probe. The blue curve shows the equivalent magnetic field reading for an electric field of 5 V/cm. The green curve shows the expected output voltage for a fluctuating magnetic field with constant amplitude of 1 μT (design-target). The gray curve is the expected magnetic fluctuation amplitude generated by the currents into the test field capacitor.
Design of a vectorial -probe. (a) The probe body and the small perpendicular coils. (b) A photograph of a finished probe head, consisting of the plasma facing ceramic tube (left), the probe body with readily wound coils (middle), and the electrical shielding (right) which is connected to ground. (c) The amplifier with matching network in the opened shielding box.
Directional calibration scan of the vectorial probe with freely chosen probe orientation. The left column shows three channels of the raw measurement. In the middle column the expected field calculated with Biot-Savart law is given. The right column shows the measured components b x , b y , and b z after application of the directional calibration.
Magnetic fluctuation spectrum of drift waves with (a) amplitude and (b) phase run. The red and blue curves show the spectrum for the probe rotated by 180° with all other parameters kept constant.
Combined magnetic field and density fluctuation scan of an m = 3 drift wave mode in azimuthal plane. The ambient magnetic field points into the plane. Fields and currents are shown for three time instants with Δt = T/4. (a) shows the density fluctuations, superposed with the isolines of the parallel current density in (c) at the levels −30, −20, …, +20 mA/cm2. The direction of the measured magnetic field components b x and b y is shown in (b).
Operational parameters of VINETA.
Tested sensor devices for measurement of magnetic field fluctuations.
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