MATHEMATICS, SIMULATION AND MODELLING
Lorentz Version 7
13 May 2009
Integrated Engineering Software
Integrated Engineering Software has updated its Lorentz simulation software to Version 7, and now includes meniscus calculations for charged particle extraction from a plasma. Lorentz is an easy-to-use solver for analysing charged particle trajectories in the presence of electric and magnetic fields.
In Lorentz 2D version 7.0, Integrated Engineering Software has introduced a new meniscus calculation procedure for numerical modelling of extraction of high-current ion beams from a plasma source. Starting from an initial estimate, the surface shape is adjusted to achieve uniform flux over the emission surface. The technique can also be applied to determine cathode shapes for uniform flux electron guns. Computer modelling of charged particle beams is an important part in the investigation of processes that take place in different electro-physical equipments. The aim of these simulations is to investigate the charge particle beam quality, which makes optimisation for a specific application possible.
The design of ion guns with plasma sources poses an extra challenge for simulation as the surface for ion extraction from plasma is not known in advance. The surface shape is determined by the balance between incoming ion flux and space-charge-limited current density. For a given extractor geometry, there is a unique surface shape that simultaneously satisfies Child's Law and ensures that the space-charge-limited current density is uniform. This shape then determines both the total current and the focusing characteristics of the beam.
Lorentz 2D can analyse the device performance, which may ultimately be limited by the ability to obtain the desired field strengths or special distributions. It may also be affected by practical problems such as producing the desired beam intensity or maintaining the beam intensity along the path, without excessive divergence due to its own space charge. Other applications may be adversely affected by unwanted charged particle motion effects, for example, multipaction in high power high frequency applications, where the desired electrical power of a device leads to problems like sparking.