Nuclear Instruments and Methods in Physics Research A 464 (2001) 587–591 Measurements of source divergence angle of pulsed nitrogen ion beams q K. Kasuya*, Y. Kishi, T. Kamiya, M. Funatsu, S. Saitoh, T. Renk 1 , B. Turman 1 , R. Leeper 1 , T. Mehlhorn 1 , J. Quintenz 1 , W. Mroz 2 Department of Energy Sciences, Tokyo Institute of Technology, Nagatsuta 4259 Midori-ku, Yokohama 226-8502, Japan Abstract Singly or doubly ionized nitrogen beams, including a small part of oxygen ion beams, were extracted from a cryogenic diode with N 2 O ice on the anode surface. The nominal diode voltage was 100–360 kV, and the peak ion current was 300 A. With a one-dimensional arrayed pinhole camera with 5 pinholes, very small divergence angle at the beam source was measured. Although, we used a very rough apparatus (not being as sophisticated as the modern version), the absolute value (measured) of the divergence angle was 5–6 mrad. This value was small enough for us to recommend this beam as one of the candidates for the future ICF or IFE driver. With the same apparatus, we observed a rather large angle of 25–60 mrad for the proton beam in our former experiment. These results indicated that this kind of medium-mass ion beam must be investigated in more detail to make clear the potential of the beam. We also developed a Thomson ion spectometer with a CCD detector, which could be applicable to the above ion beams. The energy spectrum of a proton beam was measured as the early stage preparation of the spectrometer development. # 2001 Elsevier Science B.V. All rights reserved. Keywords: Ion sources; injectors; medium-mass ion beams; Micro-divergence angle; Mass spectrometer 1. Introduction Although the light ion beam production cost is cheaper than for the heavy ion, the higher (charge to mass ratio) may prevent the future tight focus of the beam on the ICF target. On the other hand, the high beam production cost of the heavy ion together with the ambiguous production possibility of the much higher current allows us to say that the heavy ion beam is not the most hopeful candidate for the future particle beam driver. Under these considerations, the medium mass ion beam may have a poten- tial with a focusability and cost compromise. With this in mind, we tried to produce a medium mass pulsed ion beam and measure the beam divergence angle at the source. The origin of this kind of research work stems from our early work shown in [1], for example, there we produced q Supported by the Ministry of Education, Sports, Science and Culture in Japan/Japan Society for the Promotion of Science/Sandia National Laboratories/Institute of Laser Eng., Osaka University. *Corresponding author. Tel.: +81-45-924-5662; fax: +81- 45-924-5575. E-mail address: kkasuya@es.titech.ac.jp (K. Kasuya). 1 Home address: Sandia Nat. Laboratories, P.O. Box 5800, Albuquerque, NM, 87185 USA. 2 Home address: Institute of Optoelectronics, MUT, Kalis- kiergo 2, Warsaw, Poland 01-485. 0168-9002/01/$-see front matter # 2001 Elsevier Science B.V. All rights reserved. PII:S0168-9002(01)00146-2 IX. POSTER SESSION B