Abstract: The invention pertains to a method for imaging a sample by detecting ions emitted from said sample, wherein the emission of the ions to be detected is caused by a scanning particle beam impacting on said sample; and wherein detecting of the ions comprises collecting the ions; converting the collected ions to electrons and detecting the converted electrons by means of an electron detector; characterized in that the particle beam is an electron beam.

Abstract: A method of controlling an aluminum reduction cell including the following steps: maintaining alumina concentration within preset limits by alternating base, underfeed and overfeed modes; measuring cell voltage and potline amperage; calculating current normalized voltage value and a rate of changing thereof in time; comparing the calculated values of the normalized voltage with preset values thereof and correcting anode-cathode distance when passing from the base mode to the overfeed or underfeed modes; and measuring a number of alumina feed doses in the underfeed mode and overfeed mode over a time period sufficient for the alumina to dissolve.