Inertial Electrostatic Confinement Deuterium Plasma Neutron Production Study

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Inertial Electrostatic Confinement Deuterium Plasma Neutron Production Study Using Multiple Cathode Geometries Jorge R.

Inertial Electrostatic Confinement Deuterium Plasma Neutron Production Study Using Multiple Cathode Geometries Jorge R. Gaudier, Eric D. Lukosi, Ryan M. Meyer, Mark A. Prelas Nuclear Science & Engineering Institute University of Missouri-Columbia Abstract. An Inertial Electrostatic Confinement with a spherical anode of 20 in diameter and maximum voltage of 50 k. V was used with deuterium to study the relation between IEC parameters and neutrons production rates. Our aim was to improve neutron production with geometric variations to the cathode. A voltage up to 30 k. V was applied to multiple cathodes. Counts of neutrons were compared for two spherical cathodes, one of 2 in in diameter made with 3 rings and the other 3. 25 in in diameter made with 7 rings. Asymmetrical cathodes are also explored as recommended by Meyer [1] (2007). One is an oval shaped cathode made with 9 rings, 4 in from top to bottom and 3. 5 in from side to side. The other two asymmetrical cathodes have an opening which a jet escapes. Results show that asymmetrical cathodes are not optimal for neutron production and that there is and ideal cathode to anode ratio that can be attained. Data also shows that higher currents will increase neutron production as well as higher voltages which is constant with other studies. The asymmetric jet cathodes showed fewer counts in general. The shapes of these two cathodes do not provide any advantages in neutron production. On the other hand the spherical cathodes produced a very symmetrical star mode with many arms. The inlet gas, the current as well as the voltage applied, all impacted neutron production rates. If the current is too low, the counts will be low, even if the voltage is high. As the voltage increases more neutrons are produced. In Figure 8 there is one point with high (second highest) neutron production rates using 16 k. V (a low voltage), but this point had a current of 37 m. A (which is high for our system). On the other hand we have a point at the end with 30 k. V and low neutron production; for this point the current is low (5. 8 m. A). All points from 20 k. V to 30 k. V that have low number of neutron per second had a corresponding low current. When the voltage generator indicates a relatively high current (meaning high for our system), more neutrons are detected as Figure 9 illustrates. The lower neutron per seconds count rates from 20 m. A to 30 m. A corresponds to a lower voltage. Conclusion Asymmetrical cathodes that force a jet mode are not suitable for neutron production as the jet weaken the rest of the channels; perhaps for an application where a single jet of charged particles is needed as space propulsion, this cathode design might be of interest. The medium spherical cathode produced the most neutrons. The oval cathode contains two more rings than the medium spherical cathode having less transparency creating more ion-cathode collisions, producing fewer counts. Probably its oval shape contributed in producing weaker plasma because it did not produce as bright plasma as a spherical cathode. On the other hand the smaller spherical cathode could not generate a plasma strong enough to produce detectable neutrons despite being constructed with 3 rings to minimize ion loss by cathode collisions. The voltage applied to the cathode dictates neutron production but inlet gas, current and cathode geometry can improve production efficiency. As deuterium flow rates increases, the current rises and more neutrons are produced which indicates that more reactions occur. There is an ideal anode cathode ratio for maximum production which this study points towards. A balance of applied voltage, current and cathode size can be optimized. In order to determine best cathode size, spherical cathodes with same number of ring and different diameters must be tested. Once the size is determined the ideal number of cathode rings can be studied as well.