High-current discharges

Department of Physics, FEE CTU in Prague
Technicka 2, 166 27 Prague 6
phone: +420 2 2435 2331

Who we are?

We are a group at the department of physics, working in the field of basic research of hot and dense plasma, especially focusing on the high-current lightning-like discharges.

We participate in the education of the students, mostly in the PhD study program Plasma physics (at FEE CTU) and in the advanced part of the masters course at FNSPE CTU in Prague (course Physics and technique of thermonuclear fusion).

Team members

prof. RNDr. Pavel Kubeš, CSc.
Group leader. Responsible for the experiments held on the PF-1000 device in Warsaw. Manages the cooperation with the Kurchatov institute in Moscow. Specializes in processing and interpretation of the results. Principal investigator of most of the projects, which finance the activity of the group. Vice chairman of International Scientific Committee of Dense Magnetized Plasmas. Trained 8 postgraduate students and presently leads 1 more.

doc. Ing. Jozef Kravárik, CSc.
Headmaster of the Laboratory of high-current discharges at the Department of physics, member of the group, associate professor. Responsible for the preparation and testing of diagnostics. Specializes in laser diagnostics of the plasma. Responsible for the device PFZ-200, which is one of the few university devices, which can produce fusion neutrons.
 

doc. Ing. Daniel Klír, Ph.D.
Project investigator on the GIT-12 generator at the Institute of High Current Electronics in Tomsk and the HAWK generator at the US Naval Research Laboratory in Washington, DC. Further, he is responsible for experiments and collaborations with CCHEN in Chile, Faculty of Nuclear Sciences and Physical Engineering (CTU in Prague), Institute of Physics and Institute of Nuclear Physics (Czech Academy of Sciences). Since 2017, he has been the chair of the Plasma Physics Branch Board at the Faculty of Electrical Engineering, Czech Technical University in Prague.

Ing. Karel Řezáč, Ph.D.
Member of the group, supervising person for the regulatory compliance of the radiation safety in the laboratory of high-current discharges. Specializes in numerical simulations for plasma diagnostics (reconstruction of the energetic spectra of the fusion neutrons). Further specializes in design, realization and preparation of diagnostic devices. Manages the cooperation with the FME CTU in Prague, CMI in Prague and the cooperation with the company Envinet a.s.

Ing. Jakub Cikhardt
Being member of the group, he is engaged in the development of experimental electronics and diagnostics, its usage, and data interpretation during experiments on z-pinches, plasma foci, and laser systems. Currently, he is interested especially in nuclear activation diagnostics and gamma-ray spectrometry.

Ing. Vojtěch Munzar
A doctoral student, specializes in numerical simulations of fast MeV ions in magnetic fields in z-pinches, analysis and interpretation of selected data from experiments. Using numerical simulations, studies parameters of accelerated ion beams and magnetic fields in z-pinches. General theme of the PhD thesis: Effective production fast ions in z-pinch plasmas.

Ing. Balzhima Cikhardtová
She is postgraduate student. A topic of her work is focused on a laser interferometry of the plasma. With a help of this method which allow to determinate a distribution of electron density, she investigates plasma foci discharges (dynamics, instabilities, matter transport, etc.).

Ing. Ondřej Šíla
Postgraduate student. Specializes in numerical simulations with the MCNP code, which can simulate the propagation of the electromagnetic radiation, neutrons etc. through various materials. These simulations are important for design and construction of the diagnostic devices and help with the proper positioning and setting. Further serve for better understanding of the measured data. General theme of the PhD thesis: Diagnostics of the fusion neutrons in Z-pinch discharge.

Students
The activities of the Group of High-current discharges are attended by following students: David Hladík, Jan Novotný, Lucia Čabrová, Pavla Bednářová (all from FEE CTU in Prague) and Simona Buryšková (FNSP CTU in Prague).

New team member
We will gladly welcome another member of the team in any position, for example: PhD student, scientific worker, under-graduate student making bachelor or master’s thesis. The main condition is not excellent knowledge, but enthusiasm, be it in electronics, measurement, numerical simulations, etc. (our work is not only about physics).

Research directions

The main focus of our research is a high-current z-pinch which belongs to one of the most fascinating objects in plasma physics due to its natural occurrence, efficiency, and variety of applications. At present, z-pinches attract considerable interest due to their high (10%-30%) conversion efficiency of stored electrical energy into plasmas. Perhaps the best-known use of the high intrinsic efficiency of dense z-pinches is the generation of soft x-ray radiation. For instance, a z-pinch on a 20 MJ refurbished Z machine at the Sandia National Laboratories (Albuquerque, New Mexico) is now capable of producing an x-ray pulse with a 2.8 MJ radiated energy, 350 TW peak power, and 15% conversion efficiency from capacitor banks to x-rays. However, the z-pinch effect can also be used for the production of energetic particles.

Our group has been researched fusion neutron production and ion acceleration for more than 20 years. During this period, we developed new diagnostic instruments and techniques, carried out a large number of experiments on unique plasma devices, established new international collaborations (e.g. US Naval Research Laboratory in Washington DC; Sandia National Laboratories in Albuquerque, NM; Nevada Terawatt Facility in Reno, NV; Kurchatov Research Institute of Atomic Energy in Moscow, GSI Helmholtzzentrum fur Schwerionenforschung in Darmstadt, Institute of Plasma Physics and Laser Microfusion in Warsaw, Institute of High Current Electronics in Tomsk).

In 2013, we obtained breakthrough results on GIT-12 in Tomsk. We used a novel configuration of a deuterium z-pinch, and we observed efficient neutron production and acceleration of hydrogen ions to an unprecedented energy up to 40 MeV. The 40 MeV energy is several times higher than any theoretical or numerical predictions. Even though fast ions produced the first fusion neutrons in z-pinches already 60 years ago, the acceleration mechanism is still a source of debate. Considering the natural occurrence of the pinch effect in space and fusion plasmas, the study of ion acceleration in z-pinches might contribute to a deeper insight into fundamental processes in fusion and space plasmas.

What is it good for?

Our experimental results have wide possibility of usage in the following fields of study:

  • Development of a new energy source
  • Development of efficient sources producing nanosecond pulses of fast ions, electrons, neutrons and gamma rays
  • Laboratory Astrophysics,
  • Research of plasma in strong magnetic field
  • EUV lithography
  • Research of warm dense matter
  • Verification of numerical codes simulating nuclear explosions (subcritical experiments)
  • Study of the effects of nuclear weapons
  • Testing of material in nuclear weapon research
  • Development of RTG lasers, etc.

A part and a great advantage of our research are the possibilities of education and direct students' contributions to the experiments. Thanks to the individual approach of the experienced members of the team and thanks to the hardworking students, enthusiastic for the subject, quality student works are produced.

What are we working on?

PFZ-200 at FEE CTU in Prague

The home work-site for our research is the laboratory of high-current discharges at Department of physics at FEE CTU in Prague. Here we have a relatively small device PFZ-200. It is a small modified plasma focus. In its inner chamber we can produce a plasma column with 200 – 250 kA of current. The device PFZ-200 is used for: (i) Preparation and testing of the dense plasma diagnostics, which is then used for another, much bigger devices abroad. (ii) Basic research, where we study the means of accelerating the ions in the dense plasma and production of the fusion neutrons. For illustration we show the next picture, where time-evolution of the pinch discharge is shown. The pictures were made with a pin-hole camera with a MCP detector with 5 nanoseconds of exposition time. (iii) For teaching purposes in the bachelor, master and PhD study courses.

During the discharges in the device PFZ-200, acceleration of ions and electrons to high energies occurs. In these conditions X-ray radiation is generated and more energetic particles can be produced. In the case of using heavy hydrogen (deuterium) as a filling gas, fusion neutrons can be produced as well. That is why the operation of the PFZ-200 device at FEE CTU in Prague must be approved by the State Office for Nuclear Safety. Our device was classified as a simple source of ionizing radiation. It is one of the few university devices in the world, where there is the possibility to produce and measure fusion neutrons.

PF-1000 in IPPLM in Warsaw

The plasma focus device PF-1000, located in the Institute of Plasma Physics and Laser Microfusion (IPPLM) in Warsaw represents a powerful source of fusion neutrons on a medium-sized device, with currents up to 2 MA. Plasma generated by this device can be studied by a complex X-ray, neutron, interferometric and probe diagnostic in the frame of International Scientific Committee of Dense Magnetized Plasmas (ICDMP) research. In the last year the research was oriented on the study of the influence of vaporized electrode materials, on the study of the external magnetic field and on the properties of the deuterium plasma imploded by the heavier gas, for example neon.

On the left picture we present a group photo from the year 2018 in IPPLM in the front of the PF-1000 device. On the right picture you can see the visualization of the plasma discharge of the plasma focus type. The time evolution of the electron density is showed, which was reconstructed from 15 interferometry figures.

  

GIT-12 in IHCE in Tomsk

Since 2011 we cooperate with the group of Dr. Alexander Shishlov from Institute of high-current electronics (IHCE) in Tomsk, which is located in a Siberian part of Russian Federation. In this location a special generator of current pulse GIT-12 is placed. It is a terawatt generator, able to produce a current pulse with 5 MA of current and with rise-time to maximum in 250 nanoseconds or 1 microsecond. Few of the most important result lately (year 2013) are the achievement of highest observed energy of neutrons (>20 MeV) and ions (>25 MeV) in Z-pinches and second highest yield from the fusion D(d,n)3He reaction on Z-pinches (4×1012 neutrons in one shot), which means highly effective production of the fusion neutrons with intensity 1020 reactions per second.

For illustration we show on the next picture the neutron time-of-flight signals from the year 2012, which were measured by four detectors in various distances (shown left) and the reconstructed time-evolution of energy spectrum of the fusion neutrons by Monte Carlo methods (right). This neutron diagnostic is one of the most important diagnostics we use and thanks to it we can get greater understanding about the production of the fusion neutrons than other foreign workgroups. On the lower picture you can see time-integrated picture of the Z-pinch discharge, which was obtained with a pin-hole camera with diameter 100 micrometers and beryllium filter with width 25 micrometers. There are two pictures from different discharges from the year 2011 (No. 1408 and No. 1409).



Generator HAWK in NRL, Washington DC

The experiments on the HAWK generator in US Naval Research Laboratory in Washington, DC have been carried out since 2017. HAWK is a high-impedance generator delivering 0.7 MA current within 1 microsecond into a load. The HAWK generator is of the same pulsed power architecture as GIT-12. Therefore, this experiment will provide, besides new experimental data from complementary diagnostics, unique information about the scaling of charged particle acceleration and neutron production. Several experienced scientists from NRL (e.g. S. Jackson, A. Richardson, A. Beresnyak, J. Giuliani, S. Swanekamp, J.W. Schumer) participate in the joint-research project.

Other scientific work

Apart from experiments, which we design, prepare and realize on the devices PFZ-200, PF-1000 and GIT-12, we are also contacted a few times during the year with a request to operate diagnostics on other devices (laser PALS in Prague, experiments in GSI in Darmstadt, in CCHEN in Chile). For illustration we present photographs from the interaction room at the PALS laser in Prague (left) and PHELIX laser in Darmstadt (right).

  

Sponsors of our research

Our research is supported mainly by MEYS of CR, GA CR (Czech Science Foundation), CTU in Prague and IAEA. Selected research projects follow:

  • MEYS of CR, InterExcellence, Inter-Transfer LTT17015: Research in Frame of the International Center for Dense Magnetized Plasmas, 2018-2021.
  • MEYS of CR, InterExcellence, Inter-Action LTAUSA17084: High-energy processes in plasmas generated by pulsed-power devices, 2017-2020.
  • GA CR grant No. GA16-07036S: Ion acceleration mechanisms in deuterium z-pinches, 2016-2018.
  • Operational program VVV No CZ.02.1.01/0.0/0.0/16_019/0000778: Centre of Advanced Applied Sciences, 2018-2023.
  • Student grant of CTU in Prague No. 10/266/OHK3/3T/13: Electrical discharges, basic research and application, 2016-2018.
  • Program IAEA RC 17088: Characterization of High Energy Deuteron Pulses Produced by Dense Magnetized Plasmas.

Our partners

World co-operation

  • Institute of Plasma Physics and Laser Microfusion (IPPLM) in Warsaw, Poland
  • Institute of High Current Electronics (IHCE) SB RAS in Tomsk, Russian Federation
  • US Naval Research Laboratory, Washington DC, USA.
  • University of Nevada, Nevada Terawatt Facility, Reno, USA.
  • Comisión Chilena de Energía Nuclear (CCHEN) in Santiago de Chile, Chile
  • GSI Helmholtzzentrum für Schwerionenforschung (GSI) in Darmstadt, Germany
  • National Research Center Kurchatov Institute (NRC KI) in Moscow, Russian Federation

Co-operation in Czech Republic

  • Institute of Plasma Physics (IPP) AS CR, v.v.i. in Prague
  • Institute of Physics (IP) AS CR, v.v.i. in Prague
  • Faculty of Mechanical Engineering (FME) CTU in Prague
  • Faculty of Nuclear Sciences and Physical Engineering (FNSPE) CTU in Prague
  • Czech metrology institute (CMI), Prague
  • Nuclear Physics Institute (NPI) AS CR, v.v.i. in Prague
  • Envinet a.s.

Selected publications

Journal papers

Because big number of our publications and publications of our co-workers, only journal papers from 2012 follows:

  1. P. Kubes, D. Klir, J. Kravarik, K. Rezac, M. Paduch, T. Pisarczyk , M. Scholz, T. Chodukowski, I. Ivanova-Stanik, L. Karpinski, K. Tomaszewski, E. Zielinska, M. J. Sadowski: Energy Transformation in Column with Plasma Focus Discharge with MA Currents. IEEE Transactions on Plasma Science 40 (2012), 481-486.
  2. P. Kubes, V. Krauz, K. Mitrofanov, M. Paduch, M. Scholz, T. Pisarczyk , T. Chodukowski, Z. Kalinowska, L. Karpinski, D. Klir, J. Kortanek, E. Zielinska, J. Kravarik, K. Rezac: Correlation of Magnetic Probe and Neutron Signals with Interferometry Figures on the Plasma Focus Discharge. Plasma Phys. Control. Fusion 54 (2012), 105023.
  3. Klir, D., Kubes, P., Paduch, M., Pisarczyk, T., Chodukowski, T., Scholz, M., Kalinowska, Z., Bienkowska, B., Karpinski, L., Kortanek, J., Kravarik, J., Rezac, K., Ivanova-Stanik, I., Tomaszewski, K., Zielinska, E.: Search for thermonuclear neutrons in a mega-ampere plasma focus. Plasma Phys. Control. Fusion 54 (2012), 015001.
  4. Klir, D., Shishlov, A. V., Kubes, P., Rezac, K., Fursov, F. I., Kokshenev, V. A., Kovalchuk, B. M., Kravarik, J., Kurmaev, N. E., Labetsky, A. Yu, Ratakhin, N. A.: Deuterium gas puff Z-pinch at currents of 2 to 3 mega-ampere. PHYSICS OF PLASMAS 19 (2012), 032706.
  5. K. Rezac, D. Klir, P. Kubes and J. Kravarik: Improvement of time-of-flight methods for reconstruction of neutron energy spectra from D(d,n)3He fusion reactions. Plasma Phys. Control. Fusion 54 (2012), 105011.
  6. Klír, D., Kokshenev, V., Kubeš, P., Labetsky, A., Paduch, M., et al.: Search for Drive Parameter of Neutron-Optimized Z-Pinches and Dense Plasma Foci, IEEE Transactions on Plasma Science. 2013, vol. 41, no. 11, p. 3129-3134.
  7. Klír, D., Shishlov, A., Kokshenev, V., Kubeš, P., Labetsky, A., et al.: Characterization of neutron emission from mega-ampere deuterium gas puff Z-pinch at microsecond implosion times, Plasma Physics and Controlled Fusion. 2013, vol. 55, no. 8.
  8. Kubeš, P., Klír, D., Kravárik, J., Řezáč, K., Kortánek, J., et al.: Scenario of Pinch Evolution in a Plasma Focus Discharge, Plasma Physics and Controlled Fusion. 2013, vol. 55, no. 3.
  9. Kubeš, P., Paduch, M., Klír, D., Kravárik, J., Řezáč, K., et al.: Correlation of X-ray emission with interferometry and neutron diagnostics at tungsten anode face and deuterium filling in plasma-focus discharge, Plasma Physics and Controlled Fusion. 2013, vol. 55, no. 55.
  10. D. Klír, P. Kubeš, K. Řezáč, J. Cikhardt, et al.: Efficient Neutron Production from a Novel Configuration of Deuterium Gas-Puff Z-Pinch, Phys. Rev. Lett. 2014, vol. 112, art. no. 095001.
  11. J. Cikhardt, J. Krasa, M. De Marco, M. Pfeifer, A. Velyhan, E. Krousky, B. Cikhardtova, D. Klir, K. Rezac, J. Ullschmied, J. Skala, P. Kubes, J. Kravarik: Measurement of the target current by inductive probe during laser interaction on terawatt laser system, Review of Scientific Instruments 85, 10, 103507 (2014).
  12. D. Klír, J. Krása, J. Cikhardt, R. Dudzak, E. Krousky, M. Pfeifer, K. Řezáč, O. Šíla, et al.: Efficient neutron production from sub-nanosecond laser pulse accelerating deuterons on target front side, Physics of Plasmas 2015, 22(9), art. no. 093117. ISSN 1070-664X.
  13. D. Klír, A. Shishlov, V. Kokshenev, P. Kubeš, A. Labetsky, K. Řezáč, R. Cherzidov, J. Cikhardt, et al.: Efficient generation of fast neutrons by magnetized deuterons in an optimized deuterium gas-puff z-pinch, Plasma Physics and Controlled Fusion. 2015, 57(4), art. no. 044005. ISSN 0741-3335. Highlights of 2015, Cover image, LabTalk.
  14. D. Klír, A. Shishlov, V. Kokshenev, P. Kubeš, A. Labetsky, et al.: Deuterium z-pinch as a powerful source of multi-MeV ions and neutrons for advanced applications, Physics of Plasmas 2016, vol. 23, no. 3, art. no. 0327025. Editor’s Picks, Physics of Plasmas 2016. Most Read in March 2016.
  15. D. Klír, A. Shishlov, V. Kokshenev, P. Kubeš, K. Řezáč, J. Kravárik, V. Munzar, J. Cikhardt, B. Cikhardtová, et al.: Ion acceleration mechanism in mega-ampere gas-puff z-pinches, New Journal of Physics 2018, vol. 20, no. 5, art. no. 053064.

Outstanding student works and awards

  • Daniel Klír: Studium XUV a měkkého rentgenového záření v magnetických pinčích, diploma thesis, FNSPE CTU in Prague, 2002, in czech. Siemens award.
  • Karel Řezáč: Reconstruction of Neutron Energy Spectra in Z-pinch Fusion Experiments, disertation thesis, FEE CTU in Prague, 2011. Award of the rector of CTU in Prague - 1st. degree, 2012.
  • Jakub Cikhardt: POSTER 2011, 1st place in the competition – Natural science: The noise reduction of the measured signal in plasma diagnostic with adaptive filtration, May 12, 2011.
  • Jakub Cikhardt: Konstrukce rychlého bolometru pro měření intenzity impulsního měkkého rentgenového záření, diploma thesis FEE CTU in Prague, 2012, in czech. Twice awarded: Award of the dean of FEE CTU in Prague and Preciosa award 2012.
  • Group High-current discharges: Award of the rector of CTU in Prague - 2nd. degree, 2014.
  • Jakub Cikhardt: Award for an outstanding contribution on the summer school of Plasma Physics (12th Kudowa Summer School “Towards Fusion Energy”), Measurement of target current at laser system PALS using inductive probe, June 13, 2014
  • Vojtěch Munzar: Award for an outstanding contribution on the summer school of Plasma Physics (Fusion 2017), Ion beams and magnetic fields in a deuterium Z-pinch, September 15, 2018.
  • Jakub Cikhardt: Award of the dean of FEE CTU in Prague for doctoral thesis, High Energy Density Plasma Diagnostics Using Neutron and Gamma Detectors, 2018.
  • David Hladík: POSTER 2018, 1st place in the competition – Natural science: Calibration of the Silver Activation Counter of Neutrons for Laser System and Plasma Focus Experiments, May 17, 2018.