High Voltage Engineering has successfully completed the factory tests of a 3
MV Tandetron™ based accelerator system, fulfilling the rigorous requirements of the Facility for Research in Experimental ...Nuclear Astrophysics, part of the Saha Institute of Nuclear Physics, Kolkata, India. To satisfy requirements, High Voltage Engineering has developed a unique high-current light-ion injector. The injector includes two multicusp ion sources, one for H
- and one for He
+, and a Na charge exchange canal. Extensive measurements yield routine production of about 70
μA analyzed He
− and 1
mA H
−. The Tandetron™ designed and tested at 3
kW of beam power features low ripple (27
V
RMS at 3
MV), a particle transmission of at least 60% over the entire terminal voltage range, 200
kV up to 3
MV. In addition, the dual slit stabilization system ensures long term terminal voltage stability, ±30
V per hour at 3
MV.
Investigation of gas stripping at 4.1MeV for high mass negative ions Hotchkis, M.A.C.; Child, D.; Fink, D. ...
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
January 2013, 2013-01-00, 20130101, Letnik:
294
Journal Article
Recenzirano
We have used a tandem accelerator to measure charge state distributions at 4.1MeV for negative ions ranging from carbon to uranium oxide passing through the gases helium, argon and xenon. The gas ...density was varied over a wide range to observe the onset of equilibrium stripping conditions. Using a 12° electrostatic deflector after the accelerator, charge states from 1+ to 8+ have been measured. For carbon, the charge state is seen to strip progressively from a low charge of around 1+ towards equilibrium with increasing gas thickness. However, for all the other ions, there is a high probability of multiple electron loss in single collisions with the gas, leading to mean charge states greater than 2 even at very low gas stripper pressure. This effect is observed to be gas-independent.
•Sulphur hexafluoride is investigated as a stripper gas in tandem accelerators.•For heavy ions at low terminal voltage, mean charge states are found to be up to 1 charge unit higher than with argon ...gas.•Charge state distributions are found to be broader than with argon gas.•For charge states above the mean charge state, yields are typically doubled using SF6.•Using SF6 stripper gas, the efficiency of actinides AMS analysis is doubled.
We have investigated sulphur hexafluoride as a stripper gas in tandem accelerators by using the ANTARES accelerator system at ANSTO to measure charge state distributions for this gas. Results are reported at 4MV terminal voltage for injected negative ions ranging from carbon to uranium oxide. For iodine and thorium the distributions are extended across a range of energies of practical use for accelerator mass spectrometry, ion beam analysis and other accelerator applications. Charge state distributions using sulphur hexafluoride are found to have mean charge states up to 1 charge unit higher than, and to be broader than, corresponding distributions for argon gas, except in the case of carbon beams. As a result, SF6 is shown to provide significantly higher yields for charge states of heavy ions above the mean charge state. We now perform actinide AMS measurements with 9% yield to the 5+ charge state, compared to 4–5% achieved previously with argon gas.
HVE has designed a range of high-current Tandetrons
TM with terminal voltages of 1 MV up to 6 MV. Characteristic for the accelerator design is the coaxial construction of the all-solid-state power ...supply that is wrapped around the high-energy acceleration tube. Equipped with a new all-solid-state RF driver, the Tandetrons
TM are able to provide ion beams with output powers in excess of 10 kW and are as such suitable for applications like neutron production in biomedical research, boron neutron capture therapy, isotope production for positron emission tomography, as well as explosives detection using pulsed fast neutron analysis. Recently, a 1.25 MV version has passed the pre-delivery factory tests during which it was conditioned up to 1.5 MV and has delivered more than 1 mA target current. It will be used as a source of intermediate energy neutrons for the quantification of Al in human tissues. This specific application draws on the high-current capability of the Tandetron
TM. The injector is equipped with one multi-cusp ion source, but injectors can comprise two multi-cusp ion sources with output currents of up to several mA's for H/D and more than 100 μA for He. A 2 MV/1 mA version of the high-current range is currently under construction for the National Institute of Radiological Sciences (NIRS), Chiba, Japan. A recently installed 5 MV version of this range of Tandetrons
TM dedicated to scientific research has demonstrated terminal voltage ripple below 10
−5 as well as an extremely fast transient response.
Ion accelerators are fundamental in the ongoing research on materials for future energy sources, being the primary tool for understanding the behaviour of different classes of materials (functional, ...structural, diagnostic) under e.g. the intense radiation expected in fission reactors or the critical thermal operational conditions in IV generation fission reactors. The relevance of ion accelerators research extends straightforwardly to the modification and analysis of materials to be used in future developments of diverse non-nuclear sources like photovoltaic, fuel batteries, etc. From the analytical point of view, the energy of the accelerated ion needs, in many cases, to be known with a precision higher than e.g. the width of reaction resonances that are used for controlling either the yield of a reaction or the penetration depth of the ion, imposing a calibration of the accelerator terminal voltage. This paper reports on the new energy calibration performed for the 5 MV CMAM tandem accelerator.
A simple method is proposed for measuring cross-sections of fast negative atomic and molecular ions colliding with atoms and molecules. The method, applicable to tandem accelerators, uses the ...stripping process of the negative ions, occurring at the gas target placed in the accelerator high-voltage terminal. The target (stripper) gas pressure, not directly measurable, is measured with an improved version of a method that we have recently proposed. The total destruction cross-sections of negative atomic or molecular ion projectiles may be obtained, as well as those for each specific destruction channel. As an example of the validity of the method, we measured the destruction cross-sections of Si
2
− in Ar, from 30 keV to 1.3 MeV laboratory energies.
The University of Washington Model FN tandem Van de Graaff accelerator is being used for the measurement of extremely small isotopic abundance ratios, notably 14C/12C and 10Be/9Be, in a joint project ...of the Nuclear Physics Laboratory (NPL) and the Quaternary Isotope Laboratory (QL). The experimental arrangements and technical developments are described, and some preliminary results on isotopic ratios in carbon and beryllium are presented.
A standard heavy ion nuclear structure facility has been used to detect several long-lived radioisotopes by counting the accelerated ions. The problem of eliminating strong isobaric background beams ...has been solved by combining the energy loss dispersion through a uniform Al foil stack with the high momentum resolution of an Enge split-pole magnetic spectrograph. Radioisotope concentrations in the following ranges have been measured: 14C/12C = 10–12 to 10–13, 26Al/27Al = 10–10 to 10–12, 32Si/Si = 10–8 to 10–14, 36Cl/Cl = 10–8 to 10–11.
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