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Latest News
Zap Energy hits 37-million-degree electron temperatures in compact fusion device
Zap Energy announced April 23 that it has reached 1-3 keV plasma electron temperatures—roughly the equivalent of 11 to 37 million degrees Celsius—using its sheared-flow-stabilized Z-pinch approach to fusion. Reaching temperatures above that of the sun’s core (which is 10 million degrees Celsius temperature) is just one hurdle required before any fusion confinement concept can realistically pursue net gain and fusion energy.
John T. Mihalczo
Nuclear Technology | Volume 175 | Number 2 | August 2011 | Pages 498-508
Technical Paper | Radiation Measurements and General Instrumentation | doi.org/10.13182/NT11-A12320
Articles are hosted by Taylor and Francis Online.
Prompt neutron decay at delayed criticality was measured by Oak Ridge National Laboratory for uranium-reflected highly enriched uranium (HEU) and Pu metal spheres (FLATTOP), for an unreflected Pu metal (4.5% 240Pu) sphere (JEZEBEL) at Los Alamos National Laboratory (LANL) and for an unreflected HEU metal sphere at Oak Ridge Critical Experiments Facility. The average prompt neutron decay constants from hundreds of Rossi- and randomly pulsed neutron measurements with 252Cf at delayed criticality are as follows: 3.8458 ± 0.0016 × 105 s-1 , 2.2139 ± 0.0022 × 105 s-1 , 6.3126 ± 0.0100 × 105 s-1 , and 1.1061 ± 0.0009 × 106 s-1 , respectively. These values agree with previous measurements by LANL for FLATTOP, JEZEBEL, and GODIVA I as follows: 3.82 ± 0.02 × 105 s-1 for a uranium core; 2.14 ± 0.05 × 105 s-1 and 2.29 × 105 s-1 (uncertainty not reported) for a plutonium core; 6.4 ± 0.1 × 105 s-1 , and 1.1 ± 0.1 × 106 s-1 , respectively, but have smaller uncertainties because of the larger number of measurements. For the FLATTOP and JEZEBEL assemblies, the measurements agree with calculations. Traditionally, the calculated decay constants for the bare uranium metal sphere GODIVA I and the Oak Ridge Uranium Metal Sphere were higher than experimental by [approximately]10%. Other energy-dependent quantities for the bare uranium sphere agree within 1%.