BTR history

BTR code earliest version was created 1993-94. It was written in Turbo Pascal and originally intended to calculate only Re-ionized power loads from a neutral beam onto the NB Duct. The Duct geometry was reduced to a single tube with rectangular cross-section. BTR was decoded as Beam Transport with Re-ionization. Due to Turbo Pascal memory restrictions the code could operate with a limited amount of data and was extremely slow.

Later in 1995-1996 the BTR code was rewritten using Borland TP 1.5 (Delphi predecessor) for Windows 3.0. This BTR version already was supplied with Windows-like friendly interface (GUI), that allowed the user input through dialog-boxes and provided the beam tracing visualization, as well as for the load-maps. The code calculated not only the re-ionization, but also the residual ions deflection in RID. It was used to obtain the load-maps in RID for various beam optics (3, 5, 7 mrad, with/witout halo), misalignment, and steering. Besides, this version was used actively to evaluate the Magnetic Field impact on NB transport and PD loads (incl. RID). This version was really advanced for those times when a majority of physics&engineering codes were written in Fortran and had no user interface. Yet it was slow enough and memory-limited due to TP restrictions.

During 2000-2005 the code moved to Microsoft VC++. BTR specific (all-inclusive) User Interface, currently used, was designed and implemented for 2 years. Since then all the upgrades (versions 1,2,3,4) of BTR are written on VC++ using Microsoft Visual Studio (versions 4 - 13). The versions numeration started from 2005 when the code was first tested by IO team.

1. BTR 1 - slow, non-parallel;

2. BTR 2 - Multi-thread (parallel);

3. BTR 3 - with Tokamak plasma;

4. BTR 4 - Free Surfaces configuration.

5. BTR 5 - Multi-Run

6. To be continued

This is the illustrative list of Tasks which have been solved with helps of BTR at different times

• to evaluate the limits of Magnetic Field (vertical), which impose the requirements on the active magnetic shielding design - separately for 2 regions: Neutralization area and RID reflection area;

• to study the influence of different factors on the neutral beam losses, and resulting PD distributions along different elements (NBL surfaces). The main factors considered are: the beam misalignments, the Magnetic Field, the gas profiles, electrostatic field in RID, etc.

• to calculate the power maps and the injected power for a nominal set of beam parameters (Beam Source), given gas profiles and MF profiles for different modes of operation;

• to calculate the neutral beam stopping (ionization) in tokamak plasma, and shine-though power and PD map on the First Wall for given plasma parameters (depending on scenario);

• the latest BTR 4.0 version (i.e. "Free Surf", currently beta-tested) also has been actively used for beam tracing simulations in configurations very far from ITER NBI - this is possible now, due to the flexible input of geometry and beam model (incl. species and cross-sections).

• the version BTR 5.0 - Multi-Run allows running multiple Scenarios by specifying the input in SCEN_PARAM text file.