Code OK3 – An upgraded version of OK2 with beam wobbling function

Abstract

For computer simulations on heavy ion beam (HIB) irradiation onto a target with an arbitrary shape and structure in heavy ion fusion (HIF), the code OK2 was developed and presented in Computer Physics Communications 161 (2004). Code OK3 is an upgrade of OK2 including an important capability of wobbling beam illumination. The wobbling beam introduces a unique possibility for a smooth mechanism of inertial fusion target implosion, so that sufficient fusion energy is released to construct a fusion reactor in future. New version program summary Program title: OK3 Catalogue identifier: ADST_v3_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/ADST_v3_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 221 517 No. of bytes in distributed program, including test data, etc.: 2 471 015 Distribution format: tar.gz Programming language: C++ Computer: PC (Pentium 4, 1 GHz or more recommended) Operating system: Windows or UNIX RAM: 2048 MBytes Classification: 19.7 Catalogue identifier of previous version: ADST_v2_0 Journal reference of previous version: Comput. Phys. Comm. 161 (2004) 143 Does the new version supersede the previous version?: Yes Nature of problem: In heavy ion fusion (HIF), ion cancer therapy, material processing, etc., a precise beam energy deposition is essentially important [1]. Codes OK1 and OK2 have been developed to simulate the heavy ion beam energy deposition in three-dimensional arbitrary shaped targets [2, 3]. Wobbling beam illumination is important to smooth the beam energy deposition nonuniformity in HIF, so that a uniform target implosion is realized and a sufficient fusion output energy is released. Solution method: OK3 code works on the base of OK1 and OK2 [2, 3]. The code simulates a multi-beam illumination on a target with arbitrary shape and structure, including beam wobbling function. Reasons for new version: The code OK3 is based on OK2 [3] and uses the same algorithm with some improvements, the most important one is the beam wobbling function. Summary of revisions: 1. In the code OK3, beams are subdivided on many bunches. The displacement of each bunch center from the initial beam direction is calculated. 2. Code OK3 allows the beamlet number to vary from bunch to bunch. That reduces the calculation error especially in case of very complicated mesh structure with big internal holes. 3. The target temperature rises during the time of energy deposition. 4. Some procedures are improved to perform faster. 5. The energy conservation is checked up on each step of calculation process and corrected if necessary. New procedures included in OK3 1. Procedure BeamCenterRot( ) rotates the beam axis around the impinging direction of each beam. 2. Procedure BeamletRot( ) rotates the beamlet axes that belong to each beam. 3. Procedure Rotation( ) sets the coordinates of rotated beams and beamlets in chamber and pellet systems. 4. Procedure BeamletOut( ) calculates the lost energy of ions that have not impinged on the target. 5. Procedure TargetT( ) sets the temperature of the target layer of energy deposition during the irradiation process. 6. Procedure ECL( ) checks up the energy conservation law at each step of the energy deposition process. 7. Procedure ECLt( ) performs the final check up of the energy conservation law at the end of deposition process. Modified procedures in OK3 1. Procedure InitBeam( ): This procedure initializes the beam radius and coefficients A1, A2, A3, A4 and A5 for Gauss distributed beams [2]. It is enlarged in OK3 and can set beams with radii from 1 to 20 mm. 2. Procedure kBunch( ) is modified to allow beamlet number variation from bunch to bunch during the deposition. 3. Procedure ijkSp( ) and procedure Hole( ) are modified to perform faster. 4. Procedure Espl( ) and procedure ChechE( ) are modified to increase the calculation accuracy. 5. Procedure SD( ) calculates the total relative root-mean-square (RMS) deviation and the total relative peak-to-valley (PTV) deviation in energy deposition non-uniformity. This procedure is not included in code OK2 because of its limited applications (for spherical targets only). It is taken from code OK1 and modified to perform with code OK3. Running time: The execution time depends on the pellet mesh number and the number of beams in the simulated illumination as well as on the beam characteristics (beam radius on the pellet surface, beam subdivision, projectile particle energy and so on). In almost all of the practical running tests performed, the typical running time for one beam deposition is about 30 s on a PC with a CPU of Pentium 4, 2.4 GHz.