urn:nasa:pds:context:instrument:vega1.sp1 1.0 1.11.0.0 Product_Context urn:nasa:pds:context:instrument:sp1.vega1 2021-02-24 1.0 Changed inst LIDs from u:n:p:c:i:instID.scID to u:n:p:c:i:scID.instID And per "Guide toPDS4 Context Products" v1.7, changed all lidvid_reference to lid_reference urn:nasa:pds:context:instrument_host:spacecraft.vega1 instrument_to_instrument_host Reinhard, R and B. Battrick (eds), 'Space Missions to Halley's Comet', European Space Agency ESA SP-1066, ESA Pub Div, Moordwijk, Netherlands, 1986. reference.ESA-SP1066 DUST IMPACT PLASMA DETECTOR Particle Detector not applicable not applicable Instrument Overview =================== This instrument detects the electric charges contained in the plasma cloud generated by a solid particle impacting on a gold target. The principle of this technique is similar to that adopted for the impact plasma detectors of SP-2. The magnitude of the positive and negative charges is proportional to the mass of the particle Q=Am, where A= 10**3C/s for an impact velocity of 78 km/s. The SP-1 system includes two similar detectors. Each unit is made up of a base plate (1) covered by a gold target (2) at zero potential, perpendicular to the dust flow, and an array of strip collectors (4). The collectors are parallel to the dust flow; they are mounted on an insulator (3) and their edge is protected from impacts by a shield (5) connected electrically to the structure. Adjacent collectors are biased at potentials of 30 V, with opposite polarities. The two sets of electrodes in each detector detect a positive and a negative current pulse, which are analysed and recorded by the electronics unit. The entrance to one detector is covered by a plastic foil, to obtain additional information on density and/or calibration factor. The characteristic parameters of SP-1 are given in Table 8. ----------------------------------------------------------------- Table 8. Dust Particle Impact Plasma Detector characteristics Target material Gold (0.1 mm) Toil sensor area 160 cm**2, one sensor covered with 0.6 and 2 micro m thick plastic foil on Vegas-1 and 2, resp. Impact charge range 3x10**-14 -10**-8 C Estimated mass range 3x10**-17 -10**-11 g Integration time 2 s (high data rate) 2.5 min (low data rate) ----------------------------------------------------------------