Negative Ion Beam Emittance Calculations
https://doi.org/10.21122/2220-9506-2020-11-1-42-52
Abstract
Computer simulations are commonly used to support design and optimisation of powerful negative ion sources for the needs of future thermonuclear reactors like e. g. ITER. The aim of the paper was to study changes of produced beam quality (described by its emittance and brightness) with the geometry of the extraction system as well as extraction voltage.
A two-dimensional Particle-in-Cell (PIC) method based code was applied to model Hions and electrons extraction from the ion source plasma chamber through the opening with bevelled surface. The root-meansquare emittance of the extracted beam was calculated according to Chasman and Lapostolle approach. Ion beam phase space portraits were also presented to enrich the discussion.
Growth of ion (electron) beam emittance was observed both with the increasing radius of the extraction opening and the inclination of its bevelled surfaces. This degradation of beam quality is partially balanced by increasing extracted Hion current. On the other hand, increasing length of the extraction channel improves the beam quality.
It was demonstrated that for wider extraction opening the Hion beam consist of two parts coming form the two different regions of the chamber. According to calculated beam brightness the optimal wall inclination was found to be near 26o in the studied case. The decrease of the beam emittance saturates for larger channel length values. In the considered case the optimal channel length was h = 1.7 mm. The evolution of ion beam emittance and brightness shows that the best beam quality is achieved for extraction voltages between 0.5 kV and 2 kV.
Supporting agencies: The research was co-funded by th Plenipotent Representative of the Government of the Republic of Poland at JINR Dubna in the frame of the project № 75/07/2020
About the Authors
M. Turek
Maria Curie-Sklodowska University in Lublin
Poland
Poland
Address for correspondence: Marcin Turek – Institute of Physics,Maria Curie-Sklodowska University in Lublin, pl. M.Curie-Sklodowskiej 1, 20-031 Lublin, Poland. e-mail: mturek@kft.umcs.lublin.pl
P. Węgierek
Lublin University of Technology
Poland
Nadbystrzycka str., 38A, Lublin 20-618, Poland
Poland
Nadbystrzycka str., 38A, Lublin 20-618, Poland
References
1. Singh M.J., Boilson D., Polevoi A.R., Oikawa T., Mitteau R. Heating neutral beams for ITER: negative ion sources to tune fusion plasmas. New J. Phys., 2017, vol. 19, iss. 5, pp. 055004. DOI: 10.1088/1367-2630/aa639d
2. Hemsworth R., Decamps H., Graceffa J., Schunke B., Tanaka M., Dremel M., Tanga A., De Esch H.P.L., Geli F., Milnes J., Inoue T., Marcuzzi D., Sonato P., Zaccaria P. Status of the ITER heating neutral beam system. Nucl. Fusion, 2009, vol 49, no. 4, pp. 045006. DOI: 10.1088/0029-5515/49/4/045006
3. Kraus W., Fantz U., Franzen P., Fröschle M., Heinemann B., Riedl R., Wünderlich D. The development of the radio frequency driven negative ion source for neutral beam injectors. Rev. Sci. Instrum., 2012, vol. 83, pp. 02B104. DOI: 10.1063/1.3662957
4. Heinemann B., Fantz U., Kraus W., Schiesko L., Wimmer C., Wünderlich D., Bonomo F., Fröschle M., Nocentini R., Riedl R. Towards large and powerful radio frequency driven negative ion sources for fusion. New J. Phys., 2017, vol. 19, iss. 1, pp. 015001. DOI: 10.1088/1367-2630/aa520c
5. Mochalskyy S., Lifschitz A.F., Minea T. Extracted current saturation in negative ion sources. J. Appl. Phys., 2012, vol. 111, no. 11, pp. 113303. DOI: 10.1063/1.4727969
6. Mochalskyy S., Wuenderlich D., Fantz U., Franzen P., Minea T. Towards a realistic 3D simulation of the extraction region in ITER NBI relevant ion source. Nucl. Fusion, 2015, vol. 55, no. 3, pp. 033011.
7. Fubiani G., Boeuf J.P. Three-dimensional modeling of a negative ion source with a magnetic filter: impact of biasing the plasma electrode on the plasma asymmetry. Plasma Sources Sci. Technol., 2015, vol. 24, iss. 5, pp. 055001. DOI: 10.1088/0963-0252/24/5/055001
8. Nishioka S., Goto I., Miyamoto K., Hatayama A., Fukano A. Study of ion-ion plasma formation in negative ion sources by a three-dimensional in real space and three-dimensional in velocity space particle in cell model. J. Appl. Phys., 2016, vol. 119, iss. 2, pp. 023302. DOI: 10.1063/1.4939467
9. Revel A., Mochalskyy S., Montellano I.M., Fantz U., Minea T. Massive parallel 3D PIC simulation of negative ion extraction. J. Appl. Phys., 2017, vol. 122, iss. 10, pp. 103302. DOI: 10.1063/1.5001397
10. Fubiani G., Garrigues L., Hagelaar G., Kohen N., Boeuf J.P. Modeling of plasma transport and negative ion extraction in a magnetized radio-frequency plasma source. New J. of Phys., 2017, vol. 19, pp. 015002. DOI: 10.1088/1367-2630/19/1/015002
11. Taccogna F., Minelli P., Longo S. Threedimensional structure of the extraction region of a hybrid negative ion source. Plasma Sources Sci. Technol., 2013, vol. 22, no. 4, pp. 045019. DOI: 10.1088/0963-0252/22/4/045019
12. Wunderlich D., Mochalskyy S., Montellano I.M., Revel A. Review of particle-in-cell modeling for the extraction region of large negative hydrogen ion sources for fusion. Rev. Sci. Instrum., 2018, vol. 89, iss. 5, pp. 052001. DOI: 10.1063/1.5011799
13. Taccogna F., Minelli P. PIC modeling of negative ion sources for fusion. New J. Phys., 2017, vol. 19, iss. 1, pp. 015012. DOI: 10.1088/1367-2630/aa5305
14. Garrigues L., Fubiani G., Boeuf J.P. Negative ion extraction via particle simulation for fusion: critical assessment of recent contributions. Nucl. Fusion, 2017, vol. 57, no. 1, pp. 014003. DOI: 10.1088/0029-5515/57/1/014003
15. Sakurabayashi T., Hatayama A., Bacal M. Effects of a weak transverse magnetic field on negative ion transport in negative ion sources. J. Appl. Phys., 2004, vol. 95, iss. 8, pp. 3937‒3942. DOI: 10.1063/1.1682684
16. Turek M., Sielanko J. Simulations of negative ion extraction from a multi-aperture ion source in the presence of the magnetic filter. Vacuum, 2009, vol. 83, pp. S256‒ S259. DOI: 10.1016/j.vacuum.2009.01.076
17. Bacal M., Bruneteau J., Devynck P. Method for extracting volume produced negative ions. Rev. Sci. Instrum. 1988, vol. 59, pp. 2152‒2157. DOI: 10.1063/1.1139978
18. Wünderlich D., Kraus W., Fröschle M., Riedl R., Fantz U., Heinemann B., the NNBI team. Influence of the magnetic field topology on the performance of the large area negative hydrogen ion source test facility ELISE. Plasma Phys. and Control. Fusion, 2016, vol. 58, pp. 125005. DOI: 10.1088/0741-3335/58/12/125005
19. Turek M. Two-Dimensional Simulations of H¯ Ions Extraction. Acta Phys. Pol. A, 2017, vol. 132, iss. 2, pp. 254‒258. DOI: 10.12693/APhysPolA.132.254
20. Turek M. PIC simulations of plasma inside the negative ion source. Przegl. Elektrotechniczny, 2016, vol. 92(8), pp. 162‒165.|
21. Turek M. Negative Ion Beam Production in an Ion Source with Chamfered Extraction Opening. Acta Phys. Pol., 2019, vol. 136, pp. 322‒328.
22. Floettmann K. Some basic features of the beam emittance. Phys. Rev. Spec. Topics Accel. and Beams 2003, vol. 6, pp. 034202. DOI: 10.1103/PhysRevSTAB.6.034202
23. Brown I.G. (ed.) The Physics and Technology of Ion Sources. Wiley, Weinheim, 2004.
24. Turek M., Drozdziel A., Pyszniak K., Prucnal S., Żuk J. Ion source with an evaporator heated by arc discharge. Experiment and computer simulations. Przegl. Elektrotechniczny, 2010, vol. 86, pp. 193‒196.
25. Vesely F. Computational Physics: An Introduction, Springer Science & Business Media, 2001.
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For citations:
Turek M., Węgierek P. Negative Ion Beam Emittance Calculations. Devices and Methods of Measurements. 2020;11(1):42-52. https://doi.org/10.21122/2220-9506-2020-11-1-42-52
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