New Post: Simulating WB6

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New Post: Simulating WB6

Post by mattman »

New Post is Up: Simulating WB-6 ... g-wb6.html

Anyone want a PDF copy can email:

This material is meant for everyone.

Executive Summary:

This post reviews what is needed for a comprehensive simulation of the polywell. It has four sections: using WB6 as a benchmark, analytical expressions, the magnetic field in WB6 and the particle-in-cell method. Any code is first validated by duplicating the WB6 results. The machine is outline, including: the geometry, power supply, feedstock and diagnostics. Operation is summarized in five steps: tank pump down, applying the cage field, electron trapping, gas puffing and the neutrons produced. The electron emitter and beam are modeled. Beam speed is strongly controlled by emitter placement and this impacts trapping. Regardless of emitter placement, the magnetic will overpower the electric field. Energy loss from the beam is shown to be insignificant. Estimates of the field at the joint, corner and axis show that ring design emphasizes uniform containment. The axis and corner fields are close in value. The number of electron trapped is estimated. The magnetic field model for one ring of WB6 is encoded into Excel and MATLAB. The excel model required using a trapezoid approximation. Excel and MATLAB are compared against simple estimates and WB6 data, for benchmarking. Vector and energy density plots for a single ring, are generated.

The ring field is similar to the field made by two a-like poles placed close together. Therefore, the field points outward everywhere except through the rings themselves and the energy density is higher in machine center. It is suggested: that proper containment may balance the outward pointing fields and the magnetic mirror effect. This is not proven. The mathematical expression for all six rings is encoded into Excel and MATLAB. The field is modeled along three particle paths into machine center. These results are compared with expectations, estimates, single ring models and WB6 data for benchmarking. Vector and energy density plots for six rings are generated. Typical geometry, time steps and particles needed for a particle in cell simulation are given. The ion to electron ratio for WB6 is estimated at 0.98. The post concludes with nine suggestions for future work.

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