Developing an Electron Cyclotron Resonance Ion Source Computer Control System
"By using the PXI and LabVIEW platforms, control of the electron cyclotron resonance (ECR) ion source was easy, fast, and reliable. New devices and sub-systems are continuously being included in the control system now."
Updating the hardware and software systems of the electron cyclotron resonance ion source (ECRIS), which was designed and built in the 1990s at the Institute for Nuclear Research, Hungarian Academy of Sciences (ATOMKI).
Using PXI hardware and LabVIEW system design software to develop an updated control system.
Sándor Biri - MTA Atomki - Magyar Tudományos Akadémia Atommagkutató Intézet
Zoltán Perduk - MTA Atomki - Magyar Tudományos Akadémia Atommagkutató Intézet
For decades, the majority of scientific research at the Institute for Nuclear Research (ATOMKI) in Debrecen, Hungary has been based on the particle accelerators at the institute. The ATOMKI Accelerator Centre (AAC), a basic unit inside the institute, incorporates the charged particle accelerators in a complimentary way, which offers the possibility of choosing ions with various charge states, energies, and beam intensities. Currently, the AAC comprises six main facilities: a cyclotron (K=20), two Van de Graaff accelerators (1 MV, 5 MV), an electron cyclotron resonance ion source (ECRIS), an electromagnetic isotope separator, and a Tandetron, which is currently being installed. The accelerators span a range of beam energy from 50 eV to 27 MeV and attract a broad scale of research projects and applications in various fields, most commonly in nuclear and atomic physics, materials science, environmental research, and archaeology.
The ECRIS, a medium-sized facility in the family of particle accelerators, is the newest operating accelerator at ATOMKI. An ECRIS acts as a magnetic trap that confines the hot electron component of the plasma. Interaction with high-frequency electromagnetic waves heats the electrons. The frequency of the microwave (usually between 2 and 20 GHz) determines the performance of the ion source, its size, and price. The microwave-heated electrons move back and forth along the magnetic field lines during a great number of oscillations and, by space charge effects, generate the confinement of cold ions. The atoms and ions are ionized step by step to higher charge states and are finally electrostatically extracted from the plasma chamber. Figures 1 and 2 show the ATOMKI ECRIS and the electron cyclotron resonance (ECR) laboratory.
Figure 1. The ATOMKI ECRIS
Figure 2. The ECR Laboratory
In the last 20 years, ECR sources have developed into compact, high-performance ion sources for accelerators in nuclear physics and for stand-alone applications in atomic and plasma physics. The ECR sources can produce plasmas from which we can extract beams of highly charged ions of most elements of the periodical table. We can use the highly ionized beams directly for low-energy collision investigations or, by subsequent post-accelerating, for high-energy irradiations.
The ATOMKI ECRIS is not coupled to other accelerators. Instead, this stand-alone device produces highly charged plasmas and low-energy ion beams for atomic and plasma physics research and for applications. Recent plasma and ion choices include H, He, N, O, Ne, Si, Ar, Kr, and Xe from gases, and Ca, Ni, Fe, Zn, C, C60, Zn, Au, and Pb from solids. The charge of the ions in the plasma and in the beam can vary from 1 up to almost 30, depending on the element. The beam energy varies between 50 eV and 800 KeV. Numerous atomic and plasma physics investigations are being carried out in the laboratory, including plasma diagnostics, X-ray spectroscopy, ion-surface interactions, and the production of new materials.
The ECRIS Control System
The ECRIS team designed and built the ion source in the ATOMKI at the end of the 1990s. Between 1997 and 2012, direct use of the switches and potentiometers carried out 80 percent of the control of the ECRIS, and using RS232 and GPIB cards with HP VEE software carried out 20 percent of the control. This system included a Pentium-1 motherboard, Windows 95, a GPIB card, and VEE software. It served us well for the last 15 years. However, new requirements arose from the operating staff and the external users to update the hardware and software system to handle the majority of the setting parameters of the ECRIS.
We selected a PXI hardware system. We continue to develop the control software based on the LabVIEW system design software, and we received indispensable help from NI engineers during the development of the first version of the LabVIEW control software. All of the functions we used to operate under the old control system now work at the same level or better in the new configuration. We also continually include new devices in the system. Figure 3 shows the new layout of the full hardware assembly. About one-third of the electrical devices that are part of the ECRIS operate on a high-voltage platform (10 to 30 KV). Using NI fiber-optic connection cards, we can comfortably control the devices on the high-voltage platform. Figure 4 shows the staff operating the ion source. Figure 5 shows a typical display of the main control page.
Figure 3. Hardware Configuration of the ECRIS Control System
Figure 4. At the Control Desk with the New PXI System
Figure 5. The Main Data I/O Display of the Control Program
The measuring and setting tools of the ECRIS, which up until now were included in the computer-based control and data acquisition system, include the following:
- Vacuum gauge controllers
- High-voltage power supplies (ion source extraction voltage, beam current, puller electrode voltage, einzel lens voltage, sputtering electrode voltage, and current)
- High-current bending magnet (setting one required value and scanning a range)
- Bipolar power supply (biased disc)
- Picoammeter (beam current measured in a Faraday-cup)
- Microwave power (klystron amplifier)
We included these controlling elements in the new system. We are planning future developments for the new control system to reach a high level of control and data acquisition. The final goals are to:
- Include the majority of the ECRIS setting tools into a hardware-controlled group
- Save the setting I/O data together with beam spectra to make a large data library
- Shorten the plasma tuning and beam transport time by automatically recalling the saved settings
- Stabilize the energy and intensity of the beam on target for long-term measurements
- Develop the control program so the user can first remotely check the operating ion source, and later carry out the full control
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