15 cm hrubá houfnice vz. 25 15 cm hrubá houfnice vz. 25 The 15 cm hrubá houfnice vz. 25 (Heavy howitzer model 25) was a Czech heavy howitzer used in the Second World War. It was taken into Wehrmacht service as the 15 cm sFH 25(t). Slovakia had 126 in inventory. Intended to replace the various Austro-Hungarian heavy howitzer that the Czechs had inherited, they began a program to develop a new howitzer shortly after achieving independence in 1919. It didn't reflect many of the lessons of World War I as it retained a box trail and wooden wheels suitable only for horse traction. Its carriage
Field emission gun Field emission gun A field emission gun is a type of electron gun in which a sharply pointed Müller-type emitter is held at several kilovolts negative potential relative to a nearby electrode, so that there is sufficient potential gradient at the emitter surface to cause field electron emission. Emitters are either of cold-cathode type, usually made of single crystal tungsten sharpened to a tip radius of about 100 nm, or of the Schottky type, in which thermionic emission is enhanced by barrier lowering in the presence of a high electric field. Schottky emitters are made by coating a tungsten tip