Springer Handbook of Metrology and Testing by Horst Czichos Tetsuya Saito & Leslie Smith

Author:Horst Czichos, Tetsuya Saito & Leslie Smith
Language: eng
Format: epub
Publisher: Springer Berlin Heidelberg, Berlin, Heidelberg

10.3.3 Calibration [1]

10.3.3.1 Field Calibration

The field is calibrated using a small pickup coil whose effective winding area is known from an NMR calibration. The induced voltage u(t) is then fitted using (10.53), in order to determine the field calibration factor k, the damping factor and the pulse duration (including the effect of the damping)

(10.53)

The damping factor a determined in this way can be compared with the value given by a PFM circuit using a ≈ R/2L (where R is the resistivity of the pulse magnet, and L is the inductivity of the pulse magnet).

The calibration factor k is also determined as a function of the gain (integrator gain and the gain of preamplifier). The calibration factor k gives a relation between the induced voltage and the field at the search coil. At the same time the integrated voltage (using different gain factors) of the H-measuring coil (which is located at the pickup rod) on the magnetometer system is recorded.

It was shown that the calibration factor k was also determined as a function of the gain using an analogue integrator [1]. The scattering of the k factor was below ±1%. This indicates that the linearity of the gain is better than 1%. Using such a procedure, an absolute field calibration of better than 1% is achieved, including the time constants (gain) of the integrator.

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