REVIEW OF SCIENTIFIC INSTRUMENTS 85, 02B703 (2014)
A compact, versatile low-energy electron beam ion sourcea) G. Zschornack,1,b) J. König,2,c) M. Schmidt,2,c) and A. Thorn2,c) 1 Department of Physics, Dresden University of Technology, 01062 Dresden, Germany and Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, 01328 Dresden, Germany 2 DREEBIT GmbH, 01109 Dresden, Germany
(Presented 11 September 2013; received 5 September 2013; accepted 6 October 2013; published online 5 November 2013) A new compact Electron Beam Ion Source, the Dresden EBIT-LE, is introduced as an ion source working at low electron beam energies. The EBIT-LE operates at an electron energy ranging from 100 eV to some keV and can easily be modified to an EBIT also working at higher electron beam energies of up to 15 keV. We show that, depending on the electron beam energy, electron beam currents from a few mA in the low-energy regime up to about 40 mA in the high-energy regime are possible. Technical solutions as well as first experimental results of the EBIT-LE are presented. In ion extraction experiments, a stable production of low and intermediate charged ions at electron beam energies below 2 keV is demonstrated. Furthermore, X-ray spectroscopy measurements confirm the possibility of using the machine as a source of X-rays from ions excited at low electron energies. © 2013 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4826687] I. INTRODUCTION
Electron Beam Ion Sources (EBISs) were originally developed to produce highly charged ions (HCIs).1 For this purpose, high density electron beams at electron beam energies Ee higher than the ionization potential of the desired ion species are required. This leads to the development of high energy and high current devices working with superconducting magnet coils to reach the necessary electron beam compression. Later on, EBISs were discovered as useful devices for applications where intermediate and low charge states are sufficient or specifically of interest. For these applications, more efficient and less costly solutions with permanent rare-earth magnets at room-temperature were commissioned.2–5 The use of permanent magnets limits the maximum magnetic field strength resulting in lower electron current densities and, thus, lower ionization factors. However, besides their applications as HCI sources compact EBIS setups which can be operated with low electron beam energies of 2 keV or less have recently become more and more of interest for several different fields of research. They can be used as sources of electromagnetic radiation in the UV, EUV, and visible light region for calibration purposes in semiconductor industry, as reference sources for emission and absorption spectroscopy with ions of intermediate charge states in astrophysical experiments, as ion sources for research in radiation biology and medicine, and for the diagnostics of plasmas in fusion devices in the low energy range. Starting with this motivation, different attempts to construct an EBIS for the low electron energy region have been made. For example, this concerns the micro-EBIS of the Kinki Univerity (Ee = 2 keV),6 the so-called “CoBIT” (an EBIS with electron energies adjustable from 100 eV to a
few keV, applied for spectroscopic investigation of low and medium charged ions7 ), or the SH-PermEBIT (an EBIT with permanent magnets able to work in the electron beam energy range between 60 eV and 5 keV).8 In the present paper, we show that based on the existing Dresden EBIT/EBIS platform technology it is possible to modify these ion sources in a way that they can work stable near the low electron beam energy limit. In detail, we present results achieved with a moderately modified ion source of the Dresden EBIT type, the most compact source of the Dresden EBIS/T source family, which is called the Dresden EBIT-LE. The modification only consists of a decreased distance between anode and cathode in order to compensate for the lower extraction potential.
II. TECHNICAL SOLUTION
The basic setup of Dresden EBIS/T devices comprises a thermionic cathode of high emissivity followed by three collinear drift tubes, the first tube representing the anode for the electron beam, a water-cooled electron collector as well as an ion extraction lens which simultaneously acts as an electron repeller.2 Originally, the Dresden EBIT was designed to produce HCIs for a large number of elements. This requires working with relatively high ionization factors and electron beam energies despite the precondition of designing a compact table-top device. In this case, the distance between cathode and anode must be large enough to avoid electrical discharges between the two electrodes. For low energy operation, the situation is different. In contrast to the previous Dresden EBIT design it was planned to modify
a) Contributed paper, published as part of the Proceedings of the 15th
International Conference on Ion Sources, Chiba, Japan, September 2013. b) Electronic mail: [email protected] c) URL: http://www.dreebit.com
0034-6748/2014/85(2)/02B703/4/$30.00
85, 02B703-1
r the construction of the electron gun to allow for shorter cathode-anode distances to generate electron beam currents of at least a few mA at low electron acceleration potentials, © 2013 AIP Publishing LLC
02B703-2
Zschornack et al.
Rev. Sci. Instrum. 85, 02B703 (2014)
r the diameter of the anode aperture to minimize electron loss currents on the anode, and
r the electron collector design for lower electron beam power. Simulations using the program code Field Precision Xenos predicted stable electron beam conditions with the new design with acceptable beam pulsation within the drift tube region of the source. However, the maximum achievable electron beam current Ie and the extraction voltage of the electron beam Ue are related via the perveance P which is defined according to P =
Ie 3/2 Ue
.
(1)
Therefore, without taking any other losses into account and considering a space charge limited beam, the available electron beam current decreases with lower extraction voltages according to Ie ∝ Ue3/2 .
(2)
The perveance of a Dresden EBIT at standard operating parameters of 40 mA electron beam current and 8 kV extraction voltage is about 6 × 10−8 A/V3/2 . In the following, experimental results are presented which have been achieved with the Dresden EBIT-LE.
FIG. 1. Maximum electron beam current Ie measured with the EBIT-LE. The electron beam energy is calculated according to Eqs. (3) and (4). The diagram represents many data points obtained during tuning the different voltages.
strength in the center of the drift tube ensemble and characterizes the maximum electron beam compression. The Dresden EBIT usually operates with a magnetic compression on the order of 10 to 20. After several tests with other anode diameter the standard diameter was chosen since it did not effect the low-energy electron beam operation significantly. Furthermore, the standard electron collector design was tested to suit the requirements of the low-energy electron beam conditions. During the tests the EBIT-LE was operated at a base pressure of better than 1 × 109 mbar.
III. EXPERIMENTAL RESULTS A. Electron beam currents
B. Ion beam extraction at Ee ≤ 2 keV
In order to study the parameters of interest the cathode potential UC as well as the main drift tube potential U0 of the EBIT-LE were varied. The corresponding electron beam energy correlates to the extraction voltage and is given by
(4)
The ion extraction measurements were performed using the EBIT-LE in combination with a beam line setup consisting of a 90◦ dipole magnet for A/q analysis and standard ion optical components such as lenses and deflectors for ion beam guiding. Figure 2 shows a leaky mode ion extraction spectrum for xenon ions extracted with an ion energy of 932 eV/q. Additional experiments have shown that ions can be extracted
Since the cathode is operated on negative potential the absolute value of UC is given. The measured electron beam current for various cathode and main drift tube voltages is presented in Figure 1. The given maximum electron beam current values are obtained at maximum cathode temperature controlled by the maximum filament heating current. At electron energies as low as ≥100 eV a stable current of several mA can be extracted from the cathode and used for ion production within the ion trap region. The perveances in Dresden EBIT-LE operating mode compared to the standard operating mode as mentioned in Sec. II can be deduced from Figure 1. First experiments have shown that the standard design of the Dresden EBIT with a shorter cathode-anode gap is sufficient for low electron beam energy operation. The shorter cathode-anode gap was realized via an increase in length of the anode in order to keep the axial position of the cathode to ensure the magnetic compression. The magnetic compression is the ratio between magnetic field strength at the cathode emission surface and the maximum magnetic field
FIG. 2. Leaky mode xenon extraction spectra measured with the EBIT-LE. The peak structure of the individual ion charge states reflects the natural xenon isotope ratio.
Ee [keV] = Ue [kV] · e
(3)
with the elementary charge e and Ue [V] = U0 [V] + |UC |[V].
02B703-3
FIG. 3.
Zschornack et al.
Xe6 +
isotope spectrum measured with the EBIT-LE.
with energies ranging from ≈10 eV/q to 2 keV/q. The spectrum presented in Figure 2 was measured for a gas pressure inside the source of 3 × 10−9 mbar, an electron energy of Ee = 1974 eV and a current of Ie = 4.9 mA. For Xe8 + the largest ion beam current was recorded which can be explained by the complete ionization of the n = 5 main shell (the 5s2 5p6 states) and the decrease in ionization cross sections towards the next higher charge states. In Figure 3, another spectrum for xenon ions measured under the same conditions is presented. Here, the isotope splitting of the xenon ion beam can be seen including contributions in the percent range. Based on the functional principle of the ion source and the operation parameters given in Figure 1 we can derive that the ions which are produced within the ion trap at these low main drift tube voltages can be extracted to a grounded beamline with kinetic energies of ≥10 eV/q. Commonly, such low kinetic ion energies have to be realized with ion deceleration systems. In this case, the ion source and the beamline need to be set on a negative potential relative to the beam target which requires shielding attached on the entire setup. Before the target chamber, a multi-electrode deceleration lens must be installed to properly guide the beam during deceleration and avoid substantial losses. Therefore, producing ions directly at low energies represents a much more cost efficient solution which is of high interest for certain experiments where high ion currents are not required. Possible applications exist in the fields of radiation biology, molecule, and cluster beam physics, as well as ion beam chemistry.
Rev. Sci. Instrum. 85, 02B703 (2014)
FIG. 4. Neon X-ray spectrum measured at Ee = 893 eV, Ie = 13.6 mA, and an ionization time of 10 ms.
directly to the vacuum recipient of the EBIT-LE facing the electron beam under a 90◦ angle. Figure 4 shows a neon X-ray spectrum measured at 893 eV electron beam energy with Ie = 13.6 mA, an ionization time of 10 ms, and a gas pressure of 7.5 × 10−9 mbar. In comparison to the parent diagram line the measured dominant X-ray transition line is clearly shifted to higher transition energies and shows contributions of transition energies higher than the electron beam energy. Above the Ne Kα peak, X-ray satellite lines for different ion charge states q as well as transition lines from radiative recombination processes of neon ions with different charge states were recorded. Due to the low electron beam energy higher ion charge states than q = 8 are not possible. In Figure 5, an X-ray spectrum measured at Ee = 794 eV with a neon-xenon gas mixture injected into the source is displayed. Besides X-ray transition lines emitted by
C. X-ray spectroscopy at low electron energies
The first x-ray measurements were accomplished with a Si(Li) detector which has an energy resolution of 130 keV at the Mn-Kα transition line. The setup included a Be window at the detector of 8 μm thickness. The detector was attached
FIG. 5. X-ray spectrum from a neon-xenon gas mixture measured at Ee = 794 eV. Lower curve: Uncorrected spectrum as measured with the Si(Li) detector (raw data). Upper curve: Spectrum compensated for X-ray transmission through an 8 μm Be window and corrected for the detection efficiency of the Si(Li).
02B703-4
Zschornack et al.
up to helium-like neon ions Radiative Recombination (RR) transition lines from up to about nickel-like xenon ions were detected. As shown in Figures 4 and 5 low energy X-ray spectra excited at electron beam energies below 1 keV can be measured with sufficient statistics. Furthermore, beside the X-ray emission also transition lines from intermediate charged ions in the UV, EUV, and visible light range can be detected. This has been demonstrated in the past, e.g., by Xiao et al.8 and by Sakaue et al.9, 10 for EUV and visible light spectra.
IV. SUMMARY
The presented results demonstrate the ability of ion sources of the Dresden EBIS/T type for operation in the low electron beam energy region. They allow for the production of ion beams of a wide range of elements with low and intermediate charge states at low kinetic beam energies. Furthermore, Dresden EBIS/T can be used as sources of X-rays, UV, EUV, and visible light from various ion charge states excited by a low energy electron beam opening new possibilities for many fields of scientific research.
Rev. Sci. Instrum. 85, 02B703 (2014)
ACKNOWLEDGMENTS
Work supported by the European Regional Development Fund (ERDF) and the Freistaat Sachsen (Project Nos. 100074113 and 100074115). 1 E.
D. Donets, Rev. Sci. Instrum. 69, 614 (1998). P. Ovsyannikov and G. Zschornack, Rev. Sci. Instrum. 70, 2646 (1999). 3 V. P. Ovsyannikov, G. Zschornack, F. Grossmann, O. K. Koulthachev, S. Landgraf, F. Ullmann, and T. Werner, Nucl. Instrum. Methods Phys. Res. B 161–163, 1123 (2000). 4 G. Zschornack, V. P. Ovsyannikov, F. Grossmann, and O. K. Koulthachev, “Electron impact ion source,” U.S. patent 6,717,155 B1 (6 April 2004). 5 Ion source specifications and obtained results of the ion sources are available at http://www.dreebit.com, last status at 08/2013. 6 T. Kusakabe, T. Sano, Y. Yura, T. Osaka, Y. Nakajima, Y. Nakai, H. Tawara, and M. Sasao, Phys. Scr. T73, 378 (1997). 7 N. Nakamura, H. Kikuchi, H. A. Sakaue, and T. Watanabe, Rev. Sci. Instrum. 79, 063104 (2008). 8 J. Xiao, Z. Fei, Y. Yang, X. Jin, D. Lu, Y. Shen, L. Liljeby, R. Hutton, and Y. Zou, Rev. Sci. Instrum. 83, 013303 (2012). 9 H. A. Sakaue, D. Kato, N. Nakamura, E. Watanabe, N. Yamamato, C. Chen, T. Watanabe, J. Phys. Conf. Ser. 163, 012020 (2009). 10 H. A. Sakaue, N. Nakamura, E. Watanabe, A. Komatsu, and T. Watanabe, in Proceedings of the International Symposium of Electron Beam Ion Sources and Traps, Stockholm, 7–10 April (IOP Publishing for SISSA, 2010) [J. Instrum. 5, C08010 (2010)]. 2 V.
Review of Scientific Instruments is copyrighted by the American Institute of Physics (AIP). Redistribution of journal material is subject to the AIP online journal license and/or AIP copyright. For more information, see http://ojps.aip.org/rsio/rsicr.jsp
A compact, versatile low-energy electron beam ion sourcea) G. Zschornack,1,b) J. König,2,c) M. Schmidt,2,c) and A. Thorn2,c) 1 Department of Physics, Dresden University of Technology, 01062 Dresden, Germany and Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, 01328 Dresden, Germany 2 DREEBIT GmbH, 01109 Dresden, Germany
(Presented 11 September 2013; received 5 September 2013; accepted 6 October 2013; published online 5 November 2013) A new compact Electron Beam Ion Source, the Dresden EBIT-LE, is introduced as an ion source working at low electron beam energies. The EBIT-LE operates at an electron energy ranging from 100 eV to some keV and can easily be modified to an EBIT also working at higher electron beam energies of up to 15 keV. We show that, depending on the electron beam energy, electron beam currents from a few mA in the low-energy regime up to about 40 mA in the high-energy regime are possible. Technical solutions as well as first experimental results of the EBIT-LE are presented. In ion extraction experiments, a stable production of low and intermediate charged ions at electron beam energies below 2 keV is demonstrated. Furthermore, X-ray spectroscopy measurements confirm the possibility of using the machine as a source of X-rays from ions excited at low electron energies. © 2013 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4826687] I. INTRODUCTION
Electron Beam Ion Sources (EBISs) were originally developed to produce highly charged ions (HCIs).1 For this purpose, high density electron beams at electron beam energies Ee higher than the ionization potential of the desired ion species are required. This leads to the development of high energy and high current devices working with superconducting magnet coils to reach the necessary electron beam compression. Later on, EBISs were discovered as useful devices for applications where intermediate and low charge states are sufficient or specifically of interest. For these applications, more efficient and less costly solutions with permanent rare-earth magnets at room-temperature were commissioned.2–5 The use of permanent magnets limits the maximum magnetic field strength resulting in lower electron current densities and, thus, lower ionization factors. However, besides their applications as HCI sources compact EBIS setups which can be operated with low electron beam energies of 2 keV or less have recently become more and more of interest for several different fields of research. They can be used as sources of electromagnetic radiation in the UV, EUV, and visible light region for calibration purposes in semiconductor industry, as reference sources for emission and absorption spectroscopy with ions of intermediate charge states in astrophysical experiments, as ion sources for research in radiation biology and medicine, and for the diagnostics of plasmas in fusion devices in the low energy range. Starting with this motivation, different attempts to construct an EBIS for the low electron energy region have been made. For example, this concerns the micro-EBIS of the Kinki Univerity (Ee = 2 keV),6 the so-called “CoBIT” (an EBIS with electron energies adjustable from 100 eV to a
few keV, applied for spectroscopic investigation of low and medium charged ions7 ), or the SH-PermEBIT (an EBIT with permanent magnets able to work in the electron beam energy range between 60 eV and 5 keV).8 In the present paper, we show that based on the existing Dresden EBIT/EBIS platform technology it is possible to modify these ion sources in a way that they can work stable near the low electron beam energy limit. In detail, we present results achieved with a moderately modified ion source of the Dresden EBIT type, the most compact source of the Dresden EBIS/T source family, which is called the Dresden EBIT-LE. The modification only consists of a decreased distance between anode and cathode in order to compensate for the lower extraction potential.
II. TECHNICAL SOLUTION
The basic setup of Dresden EBIS/T devices comprises a thermionic cathode of high emissivity followed by three collinear drift tubes, the first tube representing the anode for the electron beam, a water-cooled electron collector as well as an ion extraction lens which simultaneously acts as an electron repeller.2 Originally, the Dresden EBIT was designed to produce HCIs for a large number of elements. This requires working with relatively high ionization factors and electron beam energies despite the precondition of designing a compact table-top device. In this case, the distance between cathode and anode must be large enough to avoid electrical discharges between the two electrodes. For low energy operation, the situation is different. In contrast to the previous Dresden EBIT design it was planned to modify
a) Contributed paper, published as part of the Proceedings of the 15th
International Conference on Ion Sources, Chiba, Japan, September 2013. b) Electronic mail: [email protected] c) URL: http://www.dreebit.com
0034-6748/2014/85(2)/02B703/4/$30.00
85, 02B703-1
r the construction of the electron gun to allow for shorter cathode-anode distances to generate electron beam currents of at least a few mA at low electron acceleration potentials, © 2013 AIP Publishing LLC
02B703-2
Zschornack et al.
Rev. Sci. Instrum. 85, 02B703 (2014)
r the diameter of the anode aperture to minimize electron loss currents on the anode, and
r the electron collector design for lower electron beam power. Simulations using the program code Field Precision Xenos predicted stable electron beam conditions with the new design with acceptable beam pulsation within the drift tube region of the source. However, the maximum achievable electron beam current Ie and the extraction voltage of the electron beam Ue are related via the perveance P which is defined according to P =
Ie 3/2 Ue
.
(1)
Therefore, without taking any other losses into account and considering a space charge limited beam, the available electron beam current decreases with lower extraction voltages according to Ie ∝ Ue3/2 .
(2)
The perveance of a Dresden EBIT at standard operating parameters of 40 mA electron beam current and 8 kV extraction voltage is about 6 × 10−8 A/V3/2 . In the following, experimental results are presented which have been achieved with the Dresden EBIT-LE.
FIG. 1. Maximum electron beam current Ie measured with the EBIT-LE. The electron beam energy is calculated according to Eqs. (3) and (4). The diagram represents many data points obtained during tuning the different voltages.
strength in the center of the drift tube ensemble and characterizes the maximum electron beam compression. The Dresden EBIT usually operates with a magnetic compression on the order of 10 to 20. After several tests with other anode diameter the standard diameter was chosen since it did not effect the low-energy electron beam operation significantly. Furthermore, the standard electron collector design was tested to suit the requirements of the low-energy electron beam conditions. During the tests the EBIT-LE was operated at a base pressure of better than 1 × 109 mbar.
III. EXPERIMENTAL RESULTS A. Electron beam currents
B. Ion beam extraction at Ee ≤ 2 keV
In order to study the parameters of interest the cathode potential UC as well as the main drift tube potential U0 of the EBIT-LE were varied. The corresponding electron beam energy correlates to the extraction voltage and is given by
(4)
The ion extraction measurements were performed using the EBIT-LE in combination with a beam line setup consisting of a 90◦ dipole magnet for A/q analysis and standard ion optical components such as lenses and deflectors for ion beam guiding. Figure 2 shows a leaky mode ion extraction spectrum for xenon ions extracted with an ion energy of 932 eV/q. Additional experiments have shown that ions can be extracted
Since the cathode is operated on negative potential the absolute value of UC is given. The measured electron beam current for various cathode and main drift tube voltages is presented in Figure 1. The given maximum electron beam current values are obtained at maximum cathode temperature controlled by the maximum filament heating current. At electron energies as low as ≥100 eV a stable current of several mA can be extracted from the cathode and used for ion production within the ion trap region. The perveances in Dresden EBIT-LE operating mode compared to the standard operating mode as mentioned in Sec. II can be deduced from Figure 1. First experiments have shown that the standard design of the Dresden EBIT with a shorter cathode-anode gap is sufficient for low electron beam energy operation. The shorter cathode-anode gap was realized via an increase in length of the anode in order to keep the axial position of the cathode to ensure the magnetic compression. The magnetic compression is the ratio between magnetic field strength at the cathode emission surface and the maximum magnetic field
FIG. 2. Leaky mode xenon extraction spectra measured with the EBIT-LE. The peak structure of the individual ion charge states reflects the natural xenon isotope ratio.
Ee [keV] = Ue [kV] · e
(3)
with the elementary charge e and Ue [V] = U0 [V] + |UC |[V].
02B703-3
FIG. 3.
Zschornack et al.
Xe6 +
isotope spectrum measured with the EBIT-LE.
with energies ranging from ≈10 eV/q to 2 keV/q. The spectrum presented in Figure 2 was measured for a gas pressure inside the source of 3 × 10−9 mbar, an electron energy of Ee = 1974 eV and a current of Ie = 4.9 mA. For Xe8 + the largest ion beam current was recorded which can be explained by the complete ionization of the n = 5 main shell (the 5s2 5p6 states) and the decrease in ionization cross sections towards the next higher charge states. In Figure 3, another spectrum for xenon ions measured under the same conditions is presented. Here, the isotope splitting of the xenon ion beam can be seen including contributions in the percent range. Based on the functional principle of the ion source and the operation parameters given in Figure 1 we can derive that the ions which are produced within the ion trap at these low main drift tube voltages can be extracted to a grounded beamline with kinetic energies of ≥10 eV/q. Commonly, such low kinetic ion energies have to be realized with ion deceleration systems. In this case, the ion source and the beamline need to be set on a negative potential relative to the beam target which requires shielding attached on the entire setup. Before the target chamber, a multi-electrode deceleration lens must be installed to properly guide the beam during deceleration and avoid substantial losses. Therefore, producing ions directly at low energies represents a much more cost efficient solution which is of high interest for certain experiments where high ion currents are not required. Possible applications exist in the fields of radiation biology, molecule, and cluster beam physics, as well as ion beam chemistry.
Rev. Sci. Instrum. 85, 02B703 (2014)
FIG. 4. Neon X-ray spectrum measured at Ee = 893 eV, Ie = 13.6 mA, and an ionization time of 10 ms.
directly to the vacuum recipient of the EBIT-LE facing the electron beam under a 90◦ angle. Figure 4 shows a neon X-ray spectrum measured at 893 eV electron beam energy with Ie = 13.6 mA, an ionization time of 10 ms, and a gas pressure of 7.5 × 10−9 mbar. In comparison to the parent diagram line the measured dominant X-ray transition line is clearly shifted to higher transition energies and shows contributions of transition energies higher than the electron beam energy. Above the Ne Kα peak, X-ray satellite lines for different ion charge states q as well as transition lines from radiative recombination processes of neon ions with different charge states were recorded. Due to the low electron beam energy higher ion charge states than q = 8 are not possible. In Figure 5, an X-ray spectrum measured at Ee = 794 eV with a neon-xenon gas mixture injected into the source is displayed. Besides X-ray transition lines emitted by
C. X-ray spectroscopy at low electron energies
The first x-ray measurements were accomplished with a Si(Li) detector which has an energy resolution of 130 keV at the Mn-Kα transition line. The setup included a Be window at the detector of 8 μm thickness. The detector was attached
FIG. 5. X-ray spectrum from a neon-xenon gas mixture measured at Ee = 794 eV. Lower curve: Uncorrected spectrum as measured with the Si(Li) detector (raw data). Upper curve: Spectrum compensated for X-ray transmission through an 8 μm Be window and corrected for the detection efficiency of the Si(Li).
02B703-4
Zschornack et al.
up to helium-like neon ions Radiative Recombination (RR) transition lines from up to about nickel-like xenon ions were detected. As shown in Figures 4 and 5 low energy X-ray spectra excited at electron beam energies below 1 keV can be measured with sufficient statistics. Furthermore, beside the X-ray emission also transition lines from intermediate charged ions in the UV, EUV, and visible light range can be detected. This has been demonstrated in the past, e.g., by Xiao et al.8 and by Sakaue et al.9, 10 for EUV and visible light spectra.
IV. SUMMARY
The presented results demonstrate the ability of ion sources of the Dresden EBIS/T type for operation in the low electron beam energy region. They allow for the production of ion beams of a wide range of elements with low and intermediate charge states at low kinetic beam energies. Furthermore, Dresden EBIS/T can be used as sources of X-rays, UV, EUV, and visible light from various ion charge states excited by a low energy electron beam opening new possibilities for many fields of scientific research.
Rev. Sci. Instrum. 85, 02B703 (2014)
ACKNOWLEDGMENTS
Work supported by the European Regional Development Fund (ERDF) and the Freistaat Sachsen (Project Nos. 100074113 and 100074115). 1 E.
D. Donets, Rev. Sci. Instrum. 69, 614 (1998). P. Ovsyannikov and G. Zschornack, Rev. Sci. Instrum. 70, 2646 (1999). 3 V. P. Ovsyannikov, G. Zschornack, F. Grossmann, O. K. Koulthachev, S. Landgraf, F. Ullmann, and T. Werner, Nucl. Instrum. Methods Phys. Res. B 161–163, 1123 (2000). 4 G. Zschornack, V. P. Ovsyannikov, F. Grossmann, and O. K. Koulthachev, “Electron impact ion source,” U.S. patent 6,717,155 B1 (6 April 2004). 5 Ion source specifications and obtained results of the ion sources are available at http://www.dreebit.com, last status at 08/2013. 6 T. Kusakabe, T. Sano, Y. Yura, T. Osaka, Y. Nakajima, Y. Nakai, H. Tawara, and M. Sasao, Phys. Scr. T73, 378 (1997). 7 N. Nakamura, H. Kikuchi, H. A. Sakaue, and T. Watanabe, Rev. Sci. Instrum. 79, 063104 (2008). 8 J. Xiao, Z. Fei, Y. Yang, X. Jin, D. Lu, Y. Shen, L. Liljeby, R. Hutton, and Y. Zou, Rev. Sci. Instrum. 83, 013303 (2012). 9 H. A. Sakaue, D. Kato, N. Nakamura, E. Watanabe, N. Yamamato, C. Chen, T. Watanabe, J. Phys. Conf. Ser. 163, 012020 (2009). 10 H. A. Sakaue, N. Nakamura, E. Watanabe, A. Komatsu, and T. Watanabe, in Proceedings of the International Symposium of Electron Beam Ion Sources and Traps, Stockholm, 7–10 April (IOP Publishing for SISSA, 2010) [J. Instrum. 5, C08010 (2010)]. 2 V.
Review of Scientific Instruments is copyrighted by the American Institute of Physics (AIP). Redistribution of journal material is subject to the AIP online journal license and/or AIP copyright. For more information, see http://ojps.aip.org/rsio/rsicr.jsp
