محمدجواد جهانشاهی

The smoke detectors can be classified into two groups: optical and ionization, the first (optical) are based on light scattering, but ionization be used for changing the plasma environment and determining smoke density or detecting it [1-3]. The common ionizational detectors, use the radioactive resource to determin the smoke density but plasma detectore be made for determining it and showing the proton affinity from non radioactive resource, also this resource be used for induction of proton from electric discharge in atmosphere, also it is able to product proton flow in atomospher pressure, that is sensitive to smoke particles and proton affinity samples, and in primary designs with present smoke and proton affinity eases, electric discharge resurce, turned off for resolving the problems in the detector, corona discharging be seperatted from proton attraction region chamber and it producted a constant proton resource [4-7]. In order to create a plasma from corona discharge was used the point - plate design. In this case, a ring was used as an target electrode in front of an needle, the needle-plate design will create a strong electric field which produces gas discharge around the needle . The detector was made of two distinct regions. The first region is ionizotion region, including two electrodes (needle and ring), the voltage was applied between the two electrodes, an electrical discharge and a flow of positive charges was created. The second region is proton capture region, includes a collecting electrode to receive positive ions. These two regions connected to each other by a tiny hole. Ions passing through the hole (due to the potential gradient), interact with smoke particles and the number of reagent ions are decreased. So the ionic current is reduced and the remaining ions move in the slope of the electrode potential to the collector and discharged. Amplifier to boost the signal received from the collector to be sent, and then to display the spectrum of the A/D card is transmitted to the computer. The detector is sensitive to smoke and Compounds high proton affinity such as ammonia and acetone. For smoke this detector has a detection limit of 21 μg / lit.