suitable properties on the walls of MCP channels.
Deposition of regular homogenious coatings with controllable electrophysical properties and good adhesion to the walls of deep narrow channels is a difficult problem. We have tested a large variety of methods of deposition of such coatings, including
· MCP impregnation in acetate, nitrate and oxalate salt solutions with consequent drying and thermic decomposition resulting in creation of oxide films on channel walls;
· deposition of oxide films on channel walls by means of decomposition of hydrooxipolimers of metals produced by sol-gel method;
· deposition of glass-enamel coatings by means of co-precipitation of components from solutions on the base of tetraetoxisilane (creation of coatings having composition close to that of standard lead-glass MCP)
· deposition of oxide coatings by MCP impregnation in alcohol solutions of oxides of acid-forming metals;
· deposition of metals on the channel walls by means of thermic “explosion” sputtering with consequent oxidation.
Unfortunately, thus made oxide coatings had nonstable electrochemical parameters due to nonhomogenious structure and bad adhesion to alumina. So we’ve developed new methods of oxide film deposition directed specifically to deposition of thin homogenious coatings on the walls of deep narrow channels
Deposition of thin oxide films from liquid phase and by means of plasma sputtering, and description of MCPs made by these methods
We’ve developed two methods of coating formation: deposition from liquid metallo-organic precursors with consequent annealing and deposition of discontinuous metal film by plasma sputtering with consequent partual oxidation. We also tested hybrid coating deposition procedure consisting of formation of partually oxidized metal film by means of plasma sputtering with consequent deposition of oxide of different metal from liquid phase.
For liquid phase deposition we used solutions of metal acetylacetonates. During annealing of acetylacetonate films the organic ligands are evaporating leaving dense homogenious oxide films with good adhesion to the surface. The best results were achieved with complex nickel-magnesium coating. Nickel oxide film was deposited first, and served to provide conductivity. Then on the top of it the magnesium oxide film was deposited, which served to provide secondary electron emission.
Method of plasma sputtering was used to deposit discontinuous film of berillium bronze which was then partually oxidized by means of heating in air atmosphere. Conductivity of such a film was more stable than that of nickel oxide film deposited from liquid phase, but its secondary emissive properties were worse than that of of the nickel-magnesium coating.
So the hybrid procedure was used where the magnesium oxide film was deposited from liquid phase on the top of berillium bronze oxide film deposited by plasma sputtering. Such a coating was combaining stable conductivity with high secondary emission coefficient.
MCP modified with all these three methods had resistivity about 1 GOhm (MCP area was 1 cm2 and thickness 100 mm). Conventional lead glass MCP have similar resistivity.
Coefficient of secondary electron emission of coatings containing magnesium oxide was rather high, probably higher than that of conventional lead glass MCP.
We’ve put MCPs of all three described above types in vacuum and applied input electron beam. In all three cases there was prevalence of output current over input current, which proves electron multiplication. The gain calculated as ratio of output to input currents, happen to be more than 1000 for plates modified with nickel-magnesium coating deposited from liquid phase, about 20 for plates with hybrid berillium-bronze-magnesium coating, and about 1.5 for plates with berillium-bronze coating.
During investigation of electron multiplication in the produced microchannel structures we