The nuclear shaped charge concept was also studied extensively in the 1980s as part of Project Prometheus, along with bomb-pumped lasers. Using a combination of explosive wave-shaping and "gun-barrel" design, up to 5% of a small nuclear bomb could reportedly be converted into kinetic energy driving a beam of particles with a beam angle of 0.001 radians (0.057 degrees), far more concentrated than the earlier-proposed plasma jet, though this decreases to 1% efficiency at 50 kilotons (half a kiloton of energy in the beam) and efficiency suffers greatly at even higher yields. There has only been one known nuclear shaped charge test, conducted in 1985 as part of Operation Grenadier. During the test, codenamed 'Chamita', the intent was to use a nuclear detonation to accelerate a one kilogram mass of tungsten at one hundred kilometers per second, in the form of small particles focused in a cone-shaped beam. The test succeeded in propelling one kilogram of tungsten/molybdenum particles to seventy kilometers per second, corresponding to the energy of about 0.59 tons of TNT. As the yield of the detonated nuclear device was 8 kilotons, this came out to only 0.007% efficiency.