ORIGINAL RESEARCH MHD Simulation for Neutron Yield, Radiations and Beam-Ion Properties in the Spherical Plasma Focus Yasar Ay 1 • Mohamed A. Abd Al-Halim 2 • Mohamed A. Bourham 1 Ó Springer Science+Business Media New York 2015 Abstract The developed spherical plasma focus model is used to investigate the neutron production and radiations emitted at the pinch. Theory of the neutron yield and radiations emitted in the radiative phase of the spherical plasma focus device is included in this paper. Since the neutron yield in the spherical plasma focus is from the beam-target neutron production mechanism, the beam-tar- get neutron production is used for calculating the neutron yield. The achieved neutron yield with 14.5 Torr of DT mixture (1:1) filling gas, 25 kV of charging voltage and 432 muF of capacitor bank is 1.3 9 10 3 . This result agrees to a large extend with other experimental measured value. The effect of the bremsstrahlung, radiative recombination and line radiations as the energy loss terms and of the Joule heating with the plasma resistance as the energy gain term on the plasma column is investigated. Plasma-ion density, beam-ion density and beam-ion speed are calculated under the diode voltage in the radiative phase of the spherical plasma focus. Keywords Spherical plasma focus  Neutron yield  Ion beam  Radiation  MHD  Simulation Introduction Neutron production with deuterium or the mixture of deuterium-tritium filling gas via nuclear fusion reactions is one of the main reasons that the plasma focus (PF) devices are studied with its cost and energy efficiency. There are two widely accepted neutron production mechanisms in the plasma focus devices, which are the thermonuclear neutron production mechanism and the beam-target neutron pro- duction mechanism [1]. While thermonuclear neutrons are produced in the thermal equilibrium in the pinch phase (or called radiative phase or slow compression phase) due to the interaction of the thermal deuterons at the maximum compression [2], the beam-target neutrons are produced in the so-called virtual diode model by the accelerated ener- getic ions hitting the relatively stationary plasma target (thermal deuterons) or ambient gas outside the plasma under the diode voltage [3], which occurs after maximum compression of the pinch. The dominant neutron production mechanisms for PF devices can be determined by the neutron anisotropy measurement, which is the neutron flux ratio in the axial direction to the radial direction with respect to anode axis [2], which also emphasizes that non-thermal beam- target neutron production mechanism has an important role in fusion reactions because while neutron anisotropy is an evidence of preferred direction for deuteron motion, there is no preferred neutron emission direction in the thermal neutron production mechanism. Two main rea- sons for neutron anisotropy are (1) the velocity direction differences between the center of mass and laboratory frame of references of the colliding deuterons, (2) the center of mass frame of reference differential cross section for the nuclear fusion reaction D þ D ! 3 He þ n & Yasar Ay yay@ncsu.edu 1 Department of Nuclear Engineering, North Carolina State University, Raleigh, NC 27695-7910, USA 2 Department of Physics, Benha University, Benha 13518, Egypt 123 J Fusion Energ DOI 10.1007/s10894-015-0046-x