Abstract
A coil-capacitor target is modeled using FEM simulations and analytical calculations, which allow to explain the time evolution of such complex target during magnetic field production driven by the flow of an extremely high current generated through the interaction with a high power laser. The numerical model includes a detailed study of the magnetic field produced by the coil-capacitor target, both in the static and transient cases, as well as magnetic force and Joule heating. The model is validated by experimental data reported in literature and can be of interest for several applications. As an example, the combination of two synchronized nanosecond lasers with the purpose of producing a plasma responsible of the proton-boron (p+ + 11B → 8.5 MeV + 3α) fusion reaction, and energizing two multi-turn coils with the main purpose of confining such a plasma could enhance the reaction rate. The preliminary conceptual design of a magnetic mirror configuration to be used for confining protons and boron ions up to a few MeV/u in a region of less than 1 mm2 is briefly reported.
Highlights
The possibility to trigger the proton-boron nuclear fusion reaction (p+ + 11B → 8.5 MeV + 3α) by using a nsec class laser has been recently demonstrated.[1,2,3,4] This is of high interest since such reaction does not produce any neutrons but just three alpha-particles, which could be used for applications in different fields
In last years it has been experimentally proved that a small coil-target energized with a long pulse, high energy laser can produce a quasi-static magnetic field of the order of 1 kT.[5,6,7,8]
It has been experimentally demonstrated that these targets can produce pulsed magnetic field in the kilo-Tesla range when energized with a long pulse, high energy laser.[5,6,7,21,22,23,24,25,26]
Summary
The experimental results used as reference in the following study are reported in Santos et al[6] The experiment was conducted at the LULI pico 2000 laser facility with a 1.057 μm wavelength, 500 ± 30 J laser energy, 1 nsec flat-top long-pulse laser beam focused on a target made of two parallel disks (3.5 mm diameter, 50 μm thickness) with a 1 mm diameter hole on the first disk enabling to focus the laser pulse into the rear disk surface. The current peak is given by the ratio between coil voltage and resistance: I = 3.216 × 105 A Such current value allows to calculate the magnetic field considering that the coil is not a closed loop. In this case the following formula can be used:. In this case only the point in the xy plane has been considered. The conductor with the horizontal part for connection with the holed disk was modeled (only by COMSOL) giving the same results as those proposed before; Figure 5 shows the field distribution on the transverse plane for the full conductor. The geometrical layout of the capacitor plate allows to collect a considerable number of electrons which are responsible for a huge charge unbalance between the two plates and as it will be shown later, its mass helps in limiting the overall thermal jump due to the coil Joule heating
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
