METHOD OF MEASURING ION CONCENTRATION AND APPARATUS FOR REALISING SAID METHOD Russian patent published in 2012 - IPC H01J47/04 

FIELD: physics.

SUBSTANCE: in the method of measuring ion concentration, involving charge accumulation on the capacitor of an aspiration chamber when ions of the analysed gas settle on its collecting electrode over a given period of time and subsequent measurement thereof by detecting a pulse arising at the output of the input device during discharge of the capacitor of the aspiration chamber on its input resistance, based on whose parameters ion concentration is determined, wherein ion concentration is determined from the integral value of that pulse, the novelty lies in that ion concentration is determined from the integral value of that pulse at the moment in time when the magnitude of the pulse satisfies the expression: n · |f_(tu) | = |e_cm| + |I_in| · R, where n is the measured ion concentration, f_(t) is a function which determines the shape of the pulse at the input of the processing device with unit ion concentration, e_cm is bias voltage of the integrator in the processing device, l_in is the input current of the integrator in the processing device, R is the resistance in the time constant of the integrator in the processing device, t_u is the time for detecting the integral of the pulse arising at the output of the input device during discharge of the capacitor of the aspiration chamber. In the apparatus for measuring ion concentration, having an aspiration chamber with a high-voltage power supply, series-connected switch, input device, processing device and indicating device, as well as a control device whose first output is connected to the processing device, the second output is connected to the switch which connects the collecting electrode of the aspiration chamber with the input device, the novelty lies in that it further includes a voltage comparator, the output signal trailing edge of which determines the time for measuring voltage across the output of the processing device using the indicating device, the first input of the comparator is connected to the input of the processing device, the second input is connected to a reference voltage source, the sign of the output voltage - U_on of which matches that of the voltage across the input of the processing device, and its magnitude is determined by the expression: |U_on| = |e_cm| + |I_in| · R, and the output of the comparator is connected to the second input of the indicating device.

EFFECT: high accuracy of measuring ion concentration by reducing measurement error caused by bias voltage and input current of the processing device.

2 cl, 7 dwg