| doughnut [`dō´nǝt] NUCLEONICS 1. Also spelled donut. 2. The toroidal vacuum chamber in which electrons are accelerated in a betatron or synchrotron. Also known as toroid. 3. An assembly of enriched fissionable material, often doughnut-shaped, used in a thermal reactor to provide a local increase in fast neutron flux for experimental purposes. PETROLEUM ENGINEERING A ring of wedges or a threaded, tapered ring that supports a pipe string. |