BTR 2.0

Guidelines for BTR 2.0 usage

BTR 2.0 screen: the injector geometry, the input settings, the process status

Although BTR-parallel branch is written as a completely new code module, it is seamlessly integrated to the BTR standard interface shell. From the user’s side there is just one more additional Start-button in the Toolbar – “Blue Comb”. It starts or resumes the parallel threads of beam tracing (i.e. BTR 2.0 itself). The standard Stop-button (“Red Cross”) in parallel mode suspends (pauses) the beam calculations been pushed once, and terminates the beam been pushed again. If the beam is paused, the Blue Comb button calls it from the last point calculated. If the beam is stopped – the beam tracing will be started from the initial point.

The button “Green Flag” is exactly the former non-parallel Start-button (“Go”). It starts the beam non-parallel tracing (i.e. BTR 1.7). This option remains active in BTR - not only for comparative trials of parallel vs. non-parallel, but because of low resources demands of BTR 1.7, allowing it to be run even on rather old PCs (Win32 is the only need). When BTR 1.7 is active, the Stop-button simply terminates the beam tracing.

BTR 2.0 is much more flexible in the results display. When the beam is stopped, the output data are assembled across the threads, and the power map on a control surface can be delivered on user’s demand in a few seconds. If the user changes the map resolution (the grid size), the load map is recalculated immediately. In BTR 2.0 the power map on a surface appears on user’s demand after the beam tracing, and its resolution can be easily changed without the beam restart, while in BTR 1.7 all the power maps are generated during the beam tracing and with prefixed resolution. With BTR 2.0 there is no more need to restart the tracing again and again in order to fit the grid size to the preferred beamlet splitting. If you want to get more detailed or smoother map on a single interesting surface, you just reset the grid size on it (via the Context menu). The minimum grid size is 1 mm, this is currently limited by the data arrays precision.

Note. If you ask to calculate a control map when the beam is paused and then resume the beam tracing, you should ask to recalculate this map at the next beam stop again, because unlike BTR 1.7, BTR 2.0 doesn’t refresh power maps on the control surfaces automatically during the beam tracing.

The example of BTR 2.0 usage

• 1. Run BTR.exe

  2. Set the desired NBL geometry in the Green Panel (F2 for update) - or read the geometry through Menu -> PDP -> NBL geom., e.g. from the file NBL_geom.txt supplied in the package.

  3. The default beam tracing options are: THIN neutralization, Trace Residual ions in RID, Trace Atoms, Re-ionization OFF. These options don’t require magnetic field or pressure to be preset. Re-ionization option can be switched on, if you have magnetic field and pressure profiles. If you accept the default beam options – just do nothing at this point.

  4. To start the beam parallel tracing click the "Blue Comb" button on the Toolbar. You'll see several message boxes before the beam actually starts. The 1st BTR message allows you to switch OFF the option of tracks visualization. Keep it switched ON this time. The 2nd BTR message informs you about the number of processors on your system and allows to change the number of parallel threads. Accept the defaults and you'll see the particles tracks on the screen (if the visualization is ON). The number of running beamlets should be equal to the number of active threads.

  5. Click the Stop-button (“Red Cross”) - the beam will be paused. If you click the Stop-button again – the beam will be terminated. You’ll see the corresponding notifications on the screen.

  6. While the beam is stopped you may check the power map on any interesting surface. Unlike BTR former versions, BTR-parallel calculates the maps after the beam tracing. Click the left mouse button on the surface’s pick-point (red point means the load will be non-zero). Then click right mouse button to activate the Context menu, and choose the map plot option (Multi-colour, Contours, 3D-view, Profiles). In a few seconds, depending on the map resolution, the map is calculated and displayed. To change the selected map resolution, choose the Grid command in the Context menu - the map will be recalculated with the new cell size.

  7. Before continuing the beam (via Blue Comb button) you may switch off the tracks visualization (Menu -> View -> Particles - unselect) – and the tracing speed will notably rise up. The size of the active task (i.e. the total number of traced particles), BTR running speed and the memory capture are displayed in the Status window (the right-bottom part of the screen).