Cyclotron Beam Dynamics Analysis

Overview
Structure of the code
Algorithm

Structure

Figure 1 shows the main window of the CBDA code. The "Pre-Processor" part of the code consists of six main blocks: "Particle", "RF system", "Injection line", "Inflector", "Cyclotron" and "Extraction".


Figure 1: CBDA main window.

The "Particle" block defines particle parameters and the selected method to take the beam space charge effects (SC) into account. The SC algorithm uses "PP" (Particle to Particle) and "PIC" (Particle In Cell with FFT application) methods. The "RF system" block defines frequency of the RF system and flat-top system parameters.

The following blocks: "Injection line", "Inflector", "Cyclotron", "Extraction" have a uniform structure. They are similar to "Geometry", "Fields", "Track" and "Bunch" blocks. The geometrical objects made in the graphical programs (AutoCAD, SolidEdge etc) are exported to the CBDA as 3DS format files. There are four 3DS files used totally. The block "Fields" defines the magnetic and electric fields needed for the beam dynamics calculations. Those fields may be in the form of the 3D map generated, for example, by TOSCA code. The analytical approximation also made by CBDA is available. The "Track" block defines the particle initial parameters: position, RF phase and momentum. The "Bunch" block generates the bunch object of four types.

The "Interactive Solution" block determines the "entrance point" and carries out the beam simulation itself (See Figure 2). The "Entrance point" means "Injection line", "Inflector" etc.



Figure 2: Solver window.

Also this part specifies the "Monitoring planes" that register the particle hits at the locations. Each block has its own monitoring planes. The "Post-Processor" part visualizes the calculation results by MathCAD and AutoCAD (Figures 3-6 are examples). Besides, creation of the animation files, in the *.avi format are also feasible. The animation reflects the characteristic features in the results obtained to understand some essential aspects of the beam simulation



Figure 3: AutoCAD visualization. Cyclotron central region. Green colour – accelerated bunches; Black colour – losses particles.



Figure 4: AutoCAD visualisation. Losses on the buncher grids. Black colour – lost particles.


Figure 5: MathCAD visualisation. Bunch configuration space after buncher grids. Particle distribution sets on the grid structure.


Figure 6: AutoCAD visualisation. 3D cyclotron central region. Bunches acceleration.

The "Cyclotron" block has an option called "Optimization". It is a new feature for the optimal design of the cyclotron central region. The CBDA code can make a central electrode structure by optimizing a new backward tracking. This method is very powerful for the multi-particle central region.




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