Mass- and Energy-analysis of Fast Ion Beams in PF-1000 by Means of a Thomson Spectrometer 1
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K. Czaus , E. Skladnik-Sadowska , K. Malinowski , R. Kwiatkowski , M.J. Sadowski , 1 2 2 2 2 3 J. Zebrowski , L. Karpinski , M. Paduch , M. Scholz , E. Zielinska and I.E. Garkusha 1
The Andrzej Soltan Institute for Nuclear Studies (IPJ), 05-400 Otwock-Swierk, Poland 2 Institute of Plasma Physics and Laser Microfusion (IPPLM), 01-497 Warsaw, Poland 3 Institute of Plasma Physics, NSC KIPT, 61-108 Kharkov, Ukraine
ABSTRACT. The paper describes measurements of energy spectra of ions emitted along the z-axis of the PF-1000 facility, which have been for the first time performed by means a miniature Thomson spectrometer during 480kJ discharges with the deuterium filling. The recorded Thomson parabolas showed that the escaping deuterons have energies in the range of 25-1000 keV, while protons (originated from hydrogen remnants) have the population of about 2 orders smaller and energies within the range of 35-300 keV.
THOMSON SPECTROMETER
EXPERIMENTAL SETUP
The PF-1000 facility was equipped with coaxial electrodes of 460 mm in length, 230 mm and 400 mm in diameter, respectively. The PF discharges were performed at the initial pressure of 2.1 hPa D2, and they were supplied from a condenser bank, charged initially to 27 kV, 480 kJ. Plasma discharges within the PF-1000 machine have been studied for many years, and some ion measurements have been performed by means of ion pinhole cameras equipped with nuclear track detectors (NTD), but only rough estimates of ion energy spectra have been made on the basis of deuteron tracks recorded behind different absorption filters The main aim of this paper was to perform a mass- and energy-analysis of the ion beams within the PF-1000 facility more accurately by means of a Thomson-type spectrometer.
View of the miniature Thomson spectrometer after a series of measurements performed in PF-1000.
EXPERIMENTAL RESULTS
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50 60 80 100 150 200 500 Inf
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25
20 mm
1 0 2
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7
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size, mm Thomson parabolas from PF-1000 obtained on a PM-355 detector, which was irradiated during deuterium four discharges (shots # 8543-8546 with 11 the total neutron yields Yn = 9.0 x 10 ) and etched under the standard conditions for 1 hour. Enlarged images of the recorded tracks (left and right column).
20 mm
protons measuring points deuterons measuring points
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7 6
35 40
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50 60 80 100 150 200 500 Inf
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size, mm
20 mm
20 mm
2
1 20 mm
size, mm
5
Ei/Zie [keV]
deuterons measuring points protons measuring points
35 40
Mi/Zie size, mm
Ei/Zie [keV]
7
Mi/Zie
30
During the studies the spectrometer was adjusted accurately along the z-axis of the PF1000 machine, and its input diaphragm was placed at a distance of 162 cm from the electrode outlets. The analyzer was pumped out through two independent channels used to reduce pressure in the skimmer and to evacuate analyzer volume behind a miniature vacuum valve. This valve made possible to separate the analyzer volume, and to exchange detectors without disturbing gas conditions in the main PF-1000 chamber.
20 mm
Thomson parabolas from PF-1000 obtained on a PM-355 detector, which was irradiated during deuterium discharges (shots # 8556-8559 with the total neutron yield Yn = 6.9 x 1011) and etched under the standard conditions for 2 hours. Enlarged images of the recorded tracks (left and right column).
EXPERIMENTAL RESULTS
Number of tracks, x106cm-2
10 7,5 5
PF-1000 shots 8543-46 deuterons protons
2,5 1 0,75 0,5 0,25 0,1 0,075 0,05
Number of tracks, x106cm-2
SUMMARYAND CONCLUSIONS The most important results of this study can be summarized as follows:
10 7,5 5
1. The Thomson measurements confirmed that the PF-1000 machine can emit intense beams of fast deuterons (and protons) and they delivered information about energy spectra of these ions.
PF-1000 shots 8556-59 protons deuterons
2,5 1 0,75 0,5
2. These results might be useful for the estimation and understanding of the acceleration processes. 3. It was shown that the miniature Thomson analyzer is a convenient diagnostic tool which might be useful for studies of other plasma-ion streams.
0,25
Measurements of the analyzing B- and E-fields might introduce considerable errors. Hence, the accurate calibration should be carried out with ions of the known energy value. It should be added that the Thomson analyzer might also be applied for timeresolved ion analysis, but it requires another detectors system.
0,1 0,075 0,05
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Energy, keV
300 400 500 700 1000
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Energy, keV
Energy spectra of deuterons and protons emitted from PF-1000, as determined from Thomson parabolas recorded for different shots performed under similar experimental conditions.
References [1] M. Scholz, B. Bienkowska, M. Borowiecki, et al., Nukleonika 51 (2006)79. [2] A. Szydłowski, L. Jakubowski, A. Banaszak, et al., Vacuum 76 (2004) 357. [3] M.J. Sadowski, K. Czaus, K. Malinowski, et al., Rev. Sci. Instrum. 80, 05304 (2009). [4] K. Malinowski, E. Składnik-Sadowska, M. J. Sadowski, Rad. Mensur. 40 (2005) 371. [5] H. Herold, A. Mozer, M. Sadowski and H. Schmidt, Rev. Sci, Instrum. 52 (1981) 24.
