Apparatus include an atmospheric pressure glow discharge (APGD) analyte electrode defining an analyte discharge axis into an APGD volume, and a plurality of APGD counter electrodes having respective electrical discharge ends directed to the APGD volume, wherein the APGD analyte electrode and the APGD counter electrodes are configured to produce an APGD plasma in the APGD volume with a voltage difference between the APGD analyte electrode and one or more of the AGPD counter electrodes. An electrode can be integrated into an ion inlet. Apparatus can be configured to perform auto-ignition and/or provide multi-modal operation through selectively powering electrodes. Electrode holder devices are disclosed. Related methods are disclosed.

Apparatus include an atmospheric pressure glow discharge (APGD) analyte electrode defining an analyte discharge axis into an APGD volume, and a plurality of APGD counter electrodes having respective electrical discharge ends directed to the APGD volume, wherein the APGD analyte electrode and the APGD counter electrodes are configured to produce an APGD plasma in the APGD volume with a voltage difference between the APGD analyte electrode and one or more of the AGPD counter electrodes. An electrode can be integrated into an ion inlet. Apparatus can be configured to perform auto-ignition and/or provide multi-modal operation through selectively powering electrodes. Electrode holder devices are disclosed. Related methods are disclosed.

The invention relates to a neutron detector unit for neutrons, in particular thermal and cold neutrons, comprising a detector housing (7, 17, 27), cathode elements and a plurality of anode elements (5, 15, 25), wherein in order to form a volume detector unit the anode elements (5, 15, 25) and the cathode elements enable a three-dimensional spatial resolution for conversion events, characterized by a converter gas in the detector housing (7, 17, 27). According to the invention, in a neutron detector arrangement which includes at least one neutron detector unit the neutron detector unit (3, 13, 23) or at least one of the neutron detector units (3, 13, 23) is oriented in such a way that at least some of the anode elements (5, 15, 25) of the at least one neutron detector unit (3, 13, 23) extend at least predominantly in a longitudinal orientation parallel or almost parallel to the direction of travel of the neutrons (4) to be detected.