The 17th International Conference on Ion Sources was hosted by CERN, the European Organization for Nuclear Research, and took place in October 2017 at Geneva’s International Conference Centre. The event covered the physics and technology of all types of ion sources for all applications.
The event was attended by 286 delegates from 28 different countries (Fig. 1). The attendees mostly come from the neutral beam injectors for fusion and the particle accelerator community, but also included industrial partners, the radioactive ion beam community as well as researchers in atomic physics and for applications including medical use and ion thrusters. At the conference, there were 50 oral presentations (split between invited and contributed) accompanied by three lively poster sessions with 200 presentations. The contributed program has been peer reviewed by the conference delegates, and it has resulted in 169 papers published in an issue of AIP Conference Proceedings. In addition, the papers from the invited program are published here in this Special Topics Section of Review of Scientific Instruments.
This Special Topic presents 13 invited contributions representative of the state of the art covering most conference topics. The Brightness Award work, won by Stockli, Welton, and Han,1 presented very careful and systematic fault analysis, optimization, and quality insurance of each of the production and conditioning processes; their efforts establish a standard for sources of negative hydrogen ions required for high duty factor accelerators requiring very high operational availability and reliability. The physics process leading to H− production and reduction of co-extracted electrons is dominated by surface production in the vicinity of the plasma meniscus (charge exchange reaction of H1-3+ and H0 impinging on a low work function cesium covered molybdenum surface and being reemitted as H− ions). Wünderlich, Mochalskyy, Montellano, and Revel presented a review of particle in cell Monte-Carlo modeling of the extraction region of large negative hydrogen ion sources for fusion.2 Wada presented the interaction between the ion source plasma and the plasma grid surface and described the hydrogen deuterium isotopic and medium mass impurity effect on the consumption of cesium.3 Kraus, Wünderlich, Fantz, Heinemann, Bonomo, and Riedl presented a record production of negative deuterium ions of utmost relevance for the fusion neutral beam injector of the fusion community.4 In RF-sources, hydrogen-cesium plasma is heated with inductively coupled radio frequencies; however, plasma heating is very energy effective when driven by an arc discharge in magnetrons or Penning H− sources as it provides suitably high electron energy distribution. Lawrie, Faircloth, Smith, Sarmento, Whitehead, Wood, Perkins, Macgregor, and Abel presented recent achievements extending the yield of high duty factor, high H− beam-current Penning sources.5
Most high-charge state or high-current ion sources require precise control of very high density and high-energy electrons; this is particularly essential for electron beam-driven ion sources. Pikin and Raparia reviewed the “Generation of Magneto-Immersed Electron Beams” for the production of laminar electron beams.6 Vondrasek, Dickerson, Hendricks, Ostroumov, Pardo, Savard, Scott, and Zinkann presented the upgrade of the CAlifornium Rare Ion Breeder Upgrade with an Electron Beam Ion Source (EBIS) ionizer.7 Achieving high charge states, high isobaric-purity and very fast charge state breeding time are the essentials of the challenging art of providing short-lived californium fission products needed for atomic and nuclear physics of exotic nuclei. At the ARIEL facility, singly charged radioisotope beams will be produced via electron-driven photo-fission and high-energy protons induced spallation, fission, and fragmentation reactions on target nuclei. Blessenohl, Dobrodey, Warnecke, Rosner, Graham, Paul, Baumann, Hockenbery, Hubele, Pfeifer, Ames, Dilling, and Crespo López-Urrutia presented an EBIS-driven charge state breeder that will ionize the exotic ion at the charge states suitable for their post acceleration.8 Improved beam purity and suitable charge to mass ratio shall extend the physics reach to heavier and new beams of radioisotopes far form stability.
Intense beams of heavy metal ions are produced via vacuum arc ion sources. Adonin and Hollinger presented the most recent research on cathode composite materials with properties matching the intensity and beam pulse duration specifications of the GSI heavy ion research accelerator facility.9 The most fundamental features of Electron Cyclotron Resonance (ECR) ion sources is the linear frequency–magnetic field relation and the plasma density quadratic scaling to the heating frequency. Tuske, Chauvin, Delferriere, Fils, and Gauthier presented the commissioning of a 2.45 GHz high intensity proton source dedicated to the new Facility for Antiproton and Ion Research (FAIR).10 It is natural to look into higher RF frequencies and to address the very challenging design of high magnetic field regions ensuring plasma heating and confinement. Zhao, Sun, Guo, Zhang, Lu, Wu, Wu, Sabbi, Juchno, Hafalia, Ravaioli, and Xie presented superconducting ECR ion sources’ results and design. ECR sources are perfectly suited for the production of high charge-state heavy ions; the SECRAL II operated with 3 heating frequencies of 28, 45, and 18 GHz achieved record beam intensities of highly ionized noble gas ions.11 The design of the first so-called fourth generation 45 GHz superconducting ECR source is presented. Thuillier, Bondoux, Angot, Baylac, Froidefond, Jacob, Lamy, Leduc, Sole, Debray, Trophime, Skalyga, and Izotov introduced a comprehensive overview of the field and presented the design and results of a 60 GHz ion source, with superconducting Nb3Sn coils for the axial magnetic mirror surrounding an innovative room temperature hexapole.12
Eventually, all of our ion sources are the trustworthy servants of a very large worldwide community of physicists; it is to meet their constantly evolving requirements that we push the boundaries of technologies and ion-source modeling. Gatignon described a glimpse of the immense variety of new physics results by selecting illustrative examples obtained at CERN’s SPS (super proton synchrotron) physics program.13 Very rare kaon decay studies rely on meson production via accelerated high-energy protons originating form duoplasmatron proton sources that, once accelerated close to the speed of light, are smashed on a fixed target. An ECR ion source provides the highly charged heavy ion necessary for the study of the phase transition to quark gluon plasma, a state of matter that existed shortly after the Big Bang in which the quarks and gluons (including those found in today’s protons and neutrons) are de-confined.
A Young Talent award, sponsored by Medicis Promed (which is supported by the European Marie Skłodowska-Curie Innovative Training Network) awarded three prizes for best presentations and posters by young scientists, with the best presentation prize being awarded to Yisel Martinez Palenzuela (KU Leuven, Belgium) and the poster prizes to Reinhard Heinke (Johannes Gutenberg University Mainz, Germany) and Johanna Pitters (CERN, Switzerland). Sincere thanks are due to all the members of the International Advisory, Local Organizing, and Scientific Programme and the Prize committees that selected the interesting program, chose the awards, and made sure that all elements of the conference ran as smoothly as possible. The event was supported by nine sponsors and industrial exhibitors: Bergoz instrumentation, D-Pace, FRIATEC, Oregon Physics, Pantechnik, PVA-TePla, Sairem, Kejin Taiji New Technology Co, and Medicis Promed. Their important contribution to our field of research is hereby acknowledged.
The 18th International Conference on Ion Sources will be held in 2019 in Lanzhou, China, and will be hosted by the Institute of Modern Physics (IMP), Chinese Academy of Science. We wish them the very best of luck in organizing the next event.
