Experimental benchmark of the NINJA code for application to the Linac4 H− ion source plasma
For a dedicated performance optimization of negative hydrogen ion sources applied at particle accelerators, a detailed assessment of the plasma processes is required. Due to the compact design of these sources, diagnostic access is typically limited to optical emission spectroscopy yielding only lin...
| Main Authors: | , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2017-01-01
|
| Series: | New Journal of Physics |
| Subjects: | |
| Online Access: | https://doi.org/10.1088/1367-2630/aa8679 |
| _version_ | 1797750543014166528 |
|---|---|
| author | S Briefi S Mattei D Rauner J Lettry M Q Tran U Fantz |
| author_facet | S Briefi S Mattei D Rauner J Lettry M Q Tran U Fantz |
| author_sort | S Briefi |
| collection | DOAJ |
| description | For a dedicated performance optimization of negative hydrogen ion sources applied at particle accelerators, a detailed assessment of the plasma processes is required. Due to the compact design of these sources, diagnostic access is typically limited to optical emission spectroscopy yielding only line-of-sight integrated results. In order to allow for a spatially resolved investigation, the electromagnetic particle-in-cell Monte Carlo collision code NINJA has been developed for the Linac4 ion source at CERN. This code considers the RF field generated by the ICP coil as well as the external static magnetic fields and calculates self-consistently the resulting discharge properties. NINJA is benchmarked at the diagnostically well accessible lab experiment CHARLIE ( C oncept studies for H elicon A ssisted R F L ow pressure I on sourc E s) at varying RF power and gas pressure. A good general agreement is observed between experiment and simulation although the simulated electron density trends for varying pressure and power as well as the absolute electron temperature values deviate slightly from the measured ones. This can be explained by the assumption of strong inductive coupling in NINJA, whereas the CHARLIE discharges show the characteristics of loosely coupled plasmas. For the Linac4 plasma, this assumption is valid. Accordingly, both the absolute values of the accessible plasma parameters and their trends for varying RF power agree well in measurement and simulation. At varying RF power, the H ^− current extracted from the Linac4 source peaks at 40 kW. For volume operation, this is perfectly reflected by assessing the processes in front of the extraction aperture based on the simulation results where the highest H ^− density is obtained for the same power level. In surface operation, the production of negative hydrogen ions at the converter surface can only be considered by specialized beam formation codes, which require plasma parameters as input. It has been demonstrated that this input can be provided reliably by the NINJA code. |
| first_indexed | 2024-03-12T16:35:16Z |
| format | Article |
| id | doaj.art-2feb0eb50d9b4b129f01fdd52b587546 |
| institution | Directory Open Access Journal |
| issn | 1367-2630 |
| language | English |
| last_indexed | 2024-03-12T16:35:16Z |
| publishDate | 2017-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | New Journal of Physics |
| spelling | doaj.art-2feb0eb50d9b4b129f01fdd52b5875462023-08-08T14:55:41ZengIOP PublishingNew Journal of Physics1367-26302017-01-01191010500610.1088/1367-2630/aa8679Experimental benchmark of the NINJA code for application to the Linac4 H− ion source plasmaS Briefi0https://orcid.org/0000-0003-2997-3503S Mattei1D Rauner2https://orcid.org/0000-0002-8739-3489J Lettry3M Q Tran4U Fantz5AG Experimentelle Plasmaphysik, Universität Augsburg , D-86135 Augsburg, GermanyCERN, CH-1211 Geneva 23, Switzerland; Swiss Plasma Center, EPFL, Station 13, CH-1015 Lausanne, SwitzerlandAG Experimentelle Plasmaphysik, Universität Augsburg , D-86135 Augsburg, Germany; Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, D-85748 Garching, GermanyCERN, CH-1211 Geneva 23, SwitzerlandSwiss Plasma Center, EPFL, Station 13, CH-1015 Lausanne, SwitzerlandAG Experimentelle Plasmaphysik, Universität Augsburg , D-86135 Augsburg, Germany; Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, D-85748 Garching, GermanyFor a dedicated performance optimization of negative hydrogen ion sources applied at particle accelerators, a detailed assessment of the plasma processes is required. Due to the compact design of these sources, diagnostic access is typically limited to optical emission spectroscopy yielding only line-of-sight integrated results. In order to allow for a spatially resolved investigation, the electromagnetic particle-in-cell Monte Carlo collision code NINJA has been developed for the Linac4 ion source at CERN. This code considers the RF field generated by the ICP coil as well as the external static magnetic fields and calculates self-consistently the resulting discharge properties. NINJA is benchmarked at the diagnostically well accessible lab experiment CHARLIE ( C oncept studies for H elicon A ssisted R F L ow pressure I on sourc E s) at varying RF power and gas pressure. A good general agreement is observed between experiment and simulation although the simulated electron density trends for varying pressure and power as well as the absolute electron temperature values deviate slightly from the measured ones. This can be explained by the assumption of strong inductive coupling in NINJA, whereas the CHARLIE discharges show the characteristics of loosely coupled plasmas. For the Linac4 plasma, this assumption is valid. Accordingly, both the absolute values of the accessible plasma parameters and their trends for varying RF power agree well in measurement and simulation. At varying RF power, the H ^− current extracted from the Linac4 source peaks at 40 kW. For volume operation, this is perfectly reflected by assessing the processes in front of the extraction aperture based on the simulation results where the highest H ^− density is obtained for the same power level. In surface operation, the production of negative hydrogen ions at the converter surface can only be considered by specialized beam formation codes, which require plasma parameters as input. It has been demonstrated that this input can be provided reliably by the NINJA code.https://doi.org/10.1088/1367-2630/aa8679negative hydrogen ion sources for acceleratorsbenchmark of PIC codeOES measurements |
| spellingShingle | S Briefi S Mattei D Rauner J Lettry M Q Tran U Fantz Experimental benchmark of the NINJA code for application to the Linac4 H− ion source plasma New Journal of Physics negative hydrogen ion sources for accelerators benchmark of PIC code OES measurements |
| title | Experimental benchmark of the NINJA code for application to the Linac4 H− ion source plasma |
| title_full | Experimental benchmark of the NINJA code for application to the Linac4 H− ion source plasma |
| title_fullStr | Experimental benchmark of the NINJA code for application to the Linac4 H− ion source plasma |
| title_full_unstemmed | Experimental benchmark of the NINJA code for application to the Linac4 H− ion source plasma |
| title_short | Experimental benchmark of the NINJA code for application to the Linac4 H− ion source plasma |
| title_sort | experimental benchmark of the ninja code for application to the linac4 h ion source plasma |
| topic | negative hydrogen ion sources for accelerators benchmark of PIC code OES measurements |
| url | https://doi.org/10.1088/1367-2630/aa8679 |
| work_keys_str_mv | AT sbriefi experimentalbenchmarkoftheninjacodeforapplicationtothelinac4hionsourceplasma AT smattei experimentalbenchmarkoftheninjacodeforapplicationtothelinac4hionsourceplasma AT drauner experimentalbenchmarkoftheninjacodeforapplicationtothelinac4hionsourceplasma AT jlettry experimentalbenchmarkoftheninjacodeforapplicationtothelinac4hionsourceplasma AT mqtran experimentalbenchmarkoftheninjacodeforapplicationtothelinac4hionsourceplasma AT ufantz experimentalbenchmarkoftheninjacodeforapplicationtothelinac4hionsourceplasma |