Accelerators Laboratory

Multidisciplinary research using charged particle beams

Publicatii Catalin M. Ticos

 

2018

C.M. Ticos, D. Ticos, J.D. Williams,

Pushing charged microscopic matter with an electron beam (submitted)

C. M. Ticos, M. Galatanu, A. Galatanu, C. Luculescu, A. Scurtu, N. Banu, D. Ticos,

Cracks and nanoparticles produced on tungsten surface by dense plasma jets

Applied Surface Science 434, 1122-1128 (2018)

 

Conferences

C.M. Ticos, D. Ticos, J.D. Williams,

Pushing charged dust with an electron beam in a plasma crystal (oral presentation)

CETAL Workshop 18-19 July 2018-INFLPR, Magurele

C.M. Ticos, D. Ticos, J.D. Williams,

Pushing charged dust with an electron beam in a plasma crystal (oral presentation)

45th EPS Conference on Plasma Physics 2-6 July 2018, Prague, Czech Republic

C.M. Ticos, D. Ticos, J.D. Williams,

Turbulent charged microparticle flow induced by the drag force of an electron beam (oral presentation)

International Balkan Workshop on Applied Physics, 10-13 July 2018, Constanta, Romania

C.M. Ticos, A. Scurtu, D. Ticos,

Solar panel cleaning on Mars with a pulsed plasma jet (oral presentation)

15th Dusty Plasma Worjshop, 29 May-1st June, 2018, Baltimore, USA

C.M. Ticos, M.L. Mitu, N. Iacob, C. Diplasu, G. Giubega, D. Ticos

Conceptual Design of Electron Spectrometer for Experiments at CETAL (poster)

Nuclear Photonics, 24-29 June, 2018, Brasov, Romania

 

2017

C.M. Ticos, A. Scurtu, D. Ticos,

A pulsed"plasma broom''for dusting off surfaces on Mars,

New Journal of Physics 19, 063006/1-11(2017)

PRESS COVERAGE in Physiscworld.com, June 9, 2017,

http://physicsworld.com/cws/article/news/2017jun/09/a-plasma-broom-for-cleaning-on-mars

Presented in the Research Highlights of Nature Physics 13, 623 (2017)

https://www.nature.com/articles/nphys4207

 

M. G. Florescu, O. G. Duliu, D. Pantazi, C. M. Ticos, D. Sporea, R. Vasilache, V. Ionescu, M. Oane,

Radiological safety assessment for the experimental area of a hyper intense laser with

Peak power of 1PW CETAL,

Radiation Protection Dosimetry 175 (1): 104-109 (2017).

 

Conferences

 C.M. Ticos, A. Scurtu, D. Ticos,

              Experimental plasma crystal interaction with an electron beam accelerated at 15 kV (oral presentation)

              8th International Confercence on the Physicd of Dusty Plasma -8ICPDP, May 20-25, Prague, Czech Republic

C.M. Ticos, A. Scurtu, D. Ticos,

              A Pulsed Plasma Jet for Dusting off Surfaces on Mars

              International Conference on Plasma Physics and Applications-CPPA 2017 Magurele, June 15-20, Romania

 

2016

Conferences

 A. Scurtu, C.M. Ticos, D. Ticos,

              Pushing dust particles with plasma jets: application to surface cleaning (poster)

              43rd European Physical Society EPS 2016, July 4-8, 2016, Leuwen, Belgium

O. Budriga, C.M. Ticos,

              Electron acceleration for space applications at the CETAL-PW laser facility (invited)

              Workshop on Complex Systems of Charged Particles and their Interaction with Electromagnetic Radiation, April 13-15, 2016, Rusia, Moscova

C.M. Ticos,

              The CETAL-PW laser facility as an irradiation facility (invited)

              COST TD1025 WG3/Bucharest Feb 29,  2016, Romania

C.M. Ticos, A. Scurtu, G. Giubega, D. Ticos,

              High speed imaging of plasmas (invited)

              Histeresis/Princeton Instruments Seminar, Feb. 2, 2016, Magurele, Romania

  

2015

N. Banu, C.M. Ticos,

                 Precession of cylindrical dust particles in the plasma sheath

                 Physics of Plasmas 22 (10), 103704 (2015)

O Budriga, E. D `Humieres, C.M. Ticos

                  Simulations for protons and electrons acceleration with the 1 PW laser pulse from CETAL facility

                  Romanian Reports in Physics 67 (4), 1271 (2015)

D. Toader, M. Oane, C.M. Ticos,

        Collimated electron beam accelerated at 12 kV from a Penning discharge

        Review of Scientific instruments 86, 013301 (2015)

C.M. Ticos, A. Scurtu, D. Toader, N. Banu,

                 Experimental demonstration of Martian soil simulant removal from a surface using a pulsed plasma jet

        Review of Scientific instruments 86, 033509 (2015)

N. Iacob, G. Schinteie, P.Palade, C.M. Ticos, V. Kuncser

        Stepped heating procedure for experimental SAR evaluation of ferrofluids

        The European Physical Journal E 38, 57 (2015)

M. Oane, A. Peled, D. Toader, P. Mursa and C.M. Ticos

     Semi-analytical solution of the thermal field distribution in a semiconductor under simultaneous irradiation by three laser fields

                 Lasers in Engineering 32 (3-4), 161 (2015)

M. Oane, I.N. Mihailescu, C.M. Ticos, N. Banu, L.M. Mitu, I. Negut , N. Mihailescu, D. Ticos

                General two photons non Fourier model for weak laser-solid interaction

                 Journal of Intense Pulsed Lasers and Applications in Advanced Physics 5 (1), 5-8 (2015)

C. P. Lungu, C. M. Ticos, C. Porosnicu, I. Jepu, M. Lungu, P. Dinca, O. Pompilian, B. Butoi, D. Ursescu, R. Banici, G. Cojocaru, R. Ungureanu, C. Luculescu, A. Marcu, A. Marin, P. Osiceanu, I. Feraru, C. Grigorescu

                Plasma plume analysis and the effect of terawatt laser system irradiation on C, W layers

                 32nd ICPIG, July 26-31, pp. 1-3 (2015), Iasi, Romania

M. Oane, D. Ticos, C.M. Ticos

                 Charged particle beams processing versus Laser processing,

                Scholars Press, pp. 1-116 (2015)

C.M. Ticos

                Highly accelerated microparticles in plasma flows

                 Romanian Reports in Physics 67 (3), 1018 (2015)

 

Conferences 2015

 C.M. Ticos,

                 The Bucharest PW at the CETAL Facility (invited talk)

                 5th CLPU Users Meeting, December 1-2, 2015, Salamanca, Spain

N. Banu, C.M. Ticos

                 Rotating dust rods in the plasma sheath between two equilibrium states (invited talk)

                 Diagnostics and simulation of dusty plasmas, 4th International Workshop, September 9 - 11, 2015, Kiel, Germany

A. Scurtu, C.M. Ticos, N. Banu, D. Toader, M.L. Mitu

                 Mars dust removal tehnique using coaxial plasma gun (poster)

                 Diagnostics and simulation of dusty plasmas, 4th International Workshop, September 9 - 11, 2015, Kiel, Germany

C. M. Ticos, G. Giubega, T. Georgescu, M. Ganciu, C. Diplasu, B. Mihalcea, M. Serbanescu, I. Dancus, L. Neagu, A. Marcu, I. Nicolae, R. Ungureanu, G. Cojocaru, O. Budriga, L. Mitu, A. Groza, D. Ticos, I. Ionita, M. Bulinski

                 Electron acceleration in gas jet at the CETAL Petawatt Laser Facility (poster)

                 ELI-NP Summer School, Sept 21-25, 2015, Magurele-Bucharest

C.M.  Ticos, C. Luculescu, A. Scurtu, D. Ticos, M. Galatanu, A. Galatanu, C.P. Lungu, C. Porosnicu, I. Jepu, G. Cojocaru, G. R. Ungureanu

                 Nano structures produce at the interaction of energetic plasma with surfaces, (invited talk)

                 International Workshop on Advances in Nanophysics and Nanophotonics Aug 31-Sept 2, 2015, Magurele, Bucharest

C.M. Ticos, M. Galatanu, C. Luculescu, M. Oane, N. Iacob, D. Ticos, A. Scurtu, N. Banu

                 Surface modification and heating of fusion compatible materials exposed to a few Mev electron beam and plasma jet (oral presentation)

                 1st EURATOM-FUSION Research Unit Days Meeting, 14th May, 2015, Institute of Atomic Physics, Bucharest, Romania

C. M. Ticos, G. Giubega, T. Georgescu, M. Ganciu, C. Diplasu, B. Mihalcea, M. Serbanescu, I. Dancus, L. Neagu, A. Marcu, I. Nicolae, R. Ungureanu, G. Cojocaru, O. Budriga, L. Mitu, A. Groza, D. Ticos, I. Ionita, M. Bulinski

                 Electron acceleration in gas jet at the CETAL Petawatt Laser Facility (poster)

                 42nd European Physical Society Conference on Plasma Physics, 22nd-26th June 2015, Lisbon, Portugal

A. Scurtu, D. Ticos, N. Banu, C. M. Ticos,

                 Efficiency of Martian dust simulant removal from surfaces in vacuum with pulsed plasma jet (poster)

                 42nd European Physical Society Conference on Plasma Physics, 22nd-26th June 2015, Lisbon, Portugal

C. P. Lungu, C. M. Ticos, C. Porosnicu, I. Jepu, M. Lungu, P. Dinca, O. Pompilian, D. Ursescu, R. Banici, G. Cojocaru, R. Ungureanu, C. Luculescu, A. Marcu, A. Marin, I. Feraru, C. Grigorescu,

                 Influenta iradierii cu laseri de putere mare (TW) a filmelor din wolfram, beriliu si carbon (poster)

                 A 14-a editie a Seminarului National de Nanostiinta si Nanotehnologie, 26 martie 2015, Bucharest, Romania

C.M. Ticos

                 Technology for manipulation and removal of dust for Mars missions (invited talk)

                 Romanian Space Week, 27-29 May 2015, Bucharest, Romania

 

2014

C. M. Ticos, D. Toader, A. Scurtu, T. Chereches, P. Lixandru

                 Dust removal from surfaces in a low pressure environment

                 Proceedings of the 41st EPS Conference on Plasma Physics, Berlin, 23 - 27 June 2014, O4J105-1/4

 M. Oane, D. Toader, N. Iacob, C. M. Ticos

        Thermal phenomena induced in a small tungsten sample during irradiation with a few MeV electron beam: Experiment versus simulations

                 Nuclear Instruments and Methods in Physics Research B 337, 17-20 (2014).

 C.P. Lungu, C. Porosnicu, I. Jepu, M. Lungu, A. Marcu, C. Luculescu, C. Ticos, A. Marin, C.E.A. Grigorescu

                 The behavior of W, Be and C layers in interaction with plasma produced by terawatt laser beam pulses

        Vacuum 110, 207-212 (2014).

M. Oane, D. Toader, N. Iacob, C. M. Ticos

    Thermal phenomena induced in a small graphite sample during irradiation with a few MeV electron beam: Experiment versus

theoretical  simulations

                 Nuclear Instruments and Methods in Physics Research B  318,  232-236 (2014).

C. P. Lungu, C. M. Ticos, C. Porosnicu, I. Jepu, M. Lungu, A. Marcu, C. Luculescu, G. Cojocaru, D. Ursescu, R. Banici, and G. R. Ungureanu

                 Periodic striations on beryllium and tungsten surfaces by indirect femtosecond laser irradiation

              Applied Physics Letters 104, 101604-1/4 (2014)

C.M. Ticos

                 Bandgaps in the dispersion of waves on a string of dust particles floating in plasma

                 U.P.B. Sci. Bull., Series A 76, 193-198 (2014)

 

2013

M. L. Mitu, D. Toader, N. Banu, A. Scurtu, C. M. Ticos

                 A 1-D Dusty Plasma Photonic Crystal

                  Journal of Applied Physics 114, 113305-1/10 (2013)

N. Banu, D. Toader, M.L. Munteanu, A. Scurtu, C. M. Ticos

                  Survey of plasma crystal symmetry

                  Journal of Optoelectronics and Advanced Materials 15, 976 -981 (2013).

C. M. Ticos, D. Toader, L. M. Munteanu, N. Banu, A. Scurtu          

                  High Speed Imaging of Dust in Plasmas         

                 Journal of Plasma Physics 79, 273--285 (2013)  

I. R. Andrei, G. V. Popescu, C. M. Ticos, M. L. Pascu

                   Optical Spectrum Analysis of Chaotic Synchronization in a Bidirectional Coupled Semiconductor Laser System

                  Proceedings of the 4th International Interdisciplinary Chaos Symposium, Editors: S.G Stavrinides, S. Banerjee, S.H. Caglar, M. Ozer,

                  Chaos and Complex Systems, pp 425-429 (2013).

D. Toader, M.L. Munteanu , N. Banu, A. Scurtu , C. M. Ticos

                  Evaluation of submillimeter electromagnetic waves scattering on dust particles in plasma

                  Journal of Optoelectronics and Advanced Materials 15, 294-298 (2013)

 

2012

C. M. Ticos, D.S. Stoica, G. L. Delzanno,

                  Generation of dust projectiles passing over an obstacle in the plasma sheath

                  Physics of Plasmas 19, 083701-1/5 (2012).

M. L. Pascu, G.V. Popescu, C. M. Ticos, I. R. Andrei,

                  Unresonant interactions of laser beams with microdroplets

                  J. European Optical Society Rapid Publication 7, 12001-1/17 (2012)

D. Toader, M. Oane, I. N. Mihailescu, C. M. Ticos, N. Serban, C. Ristoscu, K. Vutova, G. Georgescu, V. Donchev,

       Beam Dynamics: A New Computational Approach

       Electrotehnica & Electronica Conference Proceedings, pp 33-35

       Tenth Anniversary International Conference on Electron beam Technologies, Varna 1-4 June 2012, Bulgaria

 

2011

G. Salamu, O. Sandu, O., F.Voicu, M. Dejanu, D. Popa, S. Parlac, C. Ticos, N. Pavel, T. Dascalu

                  Study of flame development in 12% methane-air mixture ignited by laser

                  Optoelectronics and Advanced Materials-Rapid Communications 5 (11),  pp. 1166-1169 (2011).

C. M. Ticos, Z. Wang, G. A. Wurden

                  Observation of the Evolution of a Supersonic Plasma Jet launched by a Coaxial Gun

       IEEE Transactions on Plasma Science 39 (11), 2388-1/2 (2011).

C. M. Ticos, I. R. Andrei, M. L. Pascu, M. Bulinski,

                 Experimental Control of Power Dropouts by Current Modulation in a Semiconductor Laser with Optical Feedback,

                 Physica Scripta 83, 055402-1/5 (2011).

A. Marcu, C. M. Ticos, C. Grigoriu, I. Jepu, C. Porosnicu, A. M. Lungu, C. P. Lungu

                 Simultaneous Carbon and Tungsten Thin Film Deposition Using Two Thermionic Vacuum Arcs

                 Thin Solid Films 519, 4074 (2011).

C. M. Ticos, Z. Wang

                 Dust accelerators and their Applications in High Temperature Plasmas

                 AIP Conference Proceedings 1336 , 26 (2011)

 

2010

C. M. Ticos, I. Jepu, C. P. Lungu, P. Chiru, V. Zaroschi and A.M. Lungu

                 Removal of Floating Dust in Glow Discharge Using Plasma Jet

                 Applied Physics Letters 97,  011501/1-3 (2010).

C. M. Ticos, I. Jepu, C. P. Lungu, P. Chiru, V. Zaroschi and A.M. Lungu

                 Levitated Dust Particles Subjected to Plasma Jet
       Journal of Plasma Physics 
76, pp. 501-511 (2010).

I. R. Andrei, C. M. Ticos, M. Bulinski, M. L. Pascu
      
Chaotic behaviour in the emission of semiconductor lasers optically coupled with an external cavity
       Journal of Optoelectronics and Advanced Materials 
12 (1),  pp63-67 (2010).

C. M. Ticos

                 Experiments with a RF Dusty Plasma and an External Plasma Jet

                 AIP Conference Proceedings 1306, 180 (2010).

 

2009

D. A. Gates et al (200 co-authors alphabetical order)

                 Overview of Results from the National Spherical Torus Experiment (NSTX),

                 Nuclear Fusion 49, 104016 (2009).

C.P. Lungu, I. Mustata, A.  Anghel, C. Porosnicu, I Jepu, C. Ticos, A.M. Lungu, M. Ganciu, A. Sobetkii, G. Honciuc and P.Chapon

                 Preparation and Characterization of Multifunctional, Nanostructured Coatings Using Thermionic Vacuum Arc Method,

                 Frontiers of Applied Plasma Technology 2, pp1-6 (2009).

C. M. Ticos, I. Jepu, C. P. Lungu, P. Chiru and V. Zaroschi

                 Dust particles interaction with plasma jet

                 AIP Conference Proceedings 1188, pg 74-82 (2009).

 

2008

C. M. Ticos, Z. Wang, G. A. Wurden, J.L. Kline, D.S. Montgomery

                 Plasma Jet Acceleration of Dust Particles to Hypervelocities

                 Physics of Plasmas 15, 103701/1-9 (2008).

Z. Wang, C. M. Ticos,

                 Dust as a Versatile Matter for High-Temperature Plasma Diagnostic,

                 Review of Scientific Instruments  79, 10F333/1-3 (2008).

C. M. Ticos, Z. Wang, G. A. Wurden,

                 Experimental Plasma-Drag Acceleration of a Dust Cloud to Hypervelocities,

                 Physical Review Letters 100, 155002 (2008).

C. M. Ticos, Z. Wang, G. A. Wurden,

                  Hypervelocity Dust Storm Launched with a Coaxial Plasma Gun,

                  IEEE Transactions on Plasma Science 36 (5), 2770-2774 (2008).

D. Rasleanu, V. Ionescu, G. Prodan, V. Ciupina, C.P. Lungu, C.  Surdu-Bob, M. Osiac, O. Pompilian, M. Badulescu, A.M. Lungu, C.Ticos, V. Zaroschi ,L. Trupina, C. Miclea

                  Nanostructured PZT Type Thin Films Prepared by the Thermionic Vacuum Arc Method

                  Journal of Optoelectronics and Advanced Materials  10, 3041 (2008).

C. M. Ticos, Z. Wang, G. A. Wurden, P. K. Shukla

                  Observation of Hypervelocity Dust in Dense Supersonic Plasma Flows: Physics and Applications

                  AIP Conference Proceedings 1061, 112 (2008).

C. M. Ticos, Z. Wang, G. A. Wurden,

                  A New Parameter Regime for Dust in Plasma: the Case of Dense and Supersonic Plasma Flow,

                  AIP Conference Proceedings 1041, 135 (2008).

Z. Wang, D. K. Mansfield, L. A. Roquemore, C. M. Ticoš, G. A. Wurden,

                  Applications and Progress of Dust Injection to Fusion Technology

                  AIP Conference Proceedings 1041, 135 (2008).

Z. Wang, C.H. Skinner, G.L. Delzanno, S.I. Krasheninnikov, G.M. Lapenta, A. Yu. Pigarov, P.K. Shukla, R.D. Smirnov,

                  C. M. Ticos, W. P. West,

                  Physics of Dust in Magnetic Fusion Devices,

                  New Aspects of Plasma Physics, Proceedings of the 2007 ICTP Summer College on Plasma Physics Abdus Salam International Centre for Theoretical Physics, Trieste, Italy 30 July - 24 August 2007,p. 394-475, World Scientific (2008).

 

2007

Z. Wang, C. M. Ticos, G. A. Wurden,

                  Dust Trajectories and Applications in Plasmas Beyond Strongly-Coupled laboratory Dusty Plasmas

                  Physics of Plasmas, 14, 103701 (2007).

C. M. Ticos,

                  Ion-Driven Dust Waves in a rf Plasma Crystal,

                  Romanian Journal of Physics 52, 703 (2007)

C. M. Ticos, Z. Wang, G. A. Wurden,

                  Hypervelocity Dust Storm Launched with a Coaxial Plasma Gun

                  16th  IEEE International Pulsed Power Conference, Digest of Technical Papers, p. 1106-1109 (2007).

M. Bulinski, C.M. Ticos, R. Andrei,

                  M:N Synchronization of LFF in a Chaotic ECSL System

                  Proceedings of SPIE Vol. 6603, pp 660329/1-9 (2007).

 

2006

C. M. Ticos, Z. Wang, L. A. Dorf, G. A. Wurden,

                  A Plasmadynamic Hypervelocity Dust Injector for the National Spherical Torus Experiment,

                  Review of Scientific Instruments 77, 10E304 (2006).

C.M. Ticos, M. Bulinski, R. Andrei, M. L. Pascu,

                  Power Drop-out Control by Optical Phase Modulation in a Chaotic Semiconductor Laser

                  Journal of the Optical Society of America B 23, 2486 (2006).

C. M. Ticos, Z. Wang, G. L. Delzanno, G. Lapenta

                  Plasma Dragged Microparticles as a Method to Measure Plasma Flows

                  Physics of Plasmas 13, 103501 (2006).

L. A. Dorf, A. L. Roquemore, G. A. Wurden, C. M. Ticos, Z. Wang

                  Imaging System for Hypervelocity Dust Injection Diagnostic for NSTX

                  Review of Scientific Instruments 77, 10E517 (2006).

Z. Wang, C. M. Ticos, L. A. Dorf, G. A. Wurden,

                  Micro-particle Probes for Laboratory Plasmas

                  IEEE Transactions on Plasma Science 34, 242 (2006).

C. M. Ticos, P. W. Smith,

                  Dusty Plasmas and a Review of the Research at Oxford University,

                  Jurnal Fizik Malaysia, 27 (1), pp. 1-7 (2006).

 

2004

C. M. Ticos, A. Dyson, P.W. Smith, P. K. Shukla,

                  Pressure Triggered Collective Oscillations of a Dust Crystal in a Capacitive RF Plasma,

                  Plasma Physics and Controlled Fusion 46, B293 (2004).

C. M. Ticos, A. Dyson, P. W. Smith,

                  The Charge on Falling Dust Particles in a RF Discharge with DC Negative Bias,

                  Plasma Sources Science and Technology 13, 395 (2004).

C. M. Ticos, P. W. Smith, P. K. Shukla,

                  Oscillations of Dust Particles Due to Wake Fields: An Experimental Demonstration

                  Physica Scripta T107, 117 (2004).

 

2003 and before

C. M. Ticos, P. W. Smith, P. K. Shukla,

                  Experimental Wake-Induced Oscillations of Dust Particles in a RF Plasma,

                  Physics Letters A 319, 504 (2003).

E. Rosa, Jr., C. M. Ticos, W. B. Pardo, J. Walkenstein, M. Monti, J. Kurths,

                  Experimental Chua-Plasma Phase Synchronization of Chaos,

                  Physical Review E 68, 025202(R) (2003).

E. Rosa, Jr., C. M. Ticos, W. B. Pardo, J. Walkenstein, M. Monti, J. Kurths,

                  Phase Synchronization in a Plasma Discharge Driven by a Chaotic Signal,

                  AIP Conference Proceedings 676, 301 (2003).

W. B. Pardo, E. Rosa, Jr., C. M. Ticos, J. Walkenstein, M. Monti,

                  Pacing a Chaotic Plasma with a Music Signal,

                  Physics Letters A 284, 259-265 (2001).

C. M. Ticos, E. Rosa, Jr., W. B. Pardo, J. Walkenstein, M. Monti,

                  Experimental Real Time Phase Synchronization of a Paced Chaotic Plasma Discharge

                  Physical Review Letters 85, 2929 (2000).

E. Rosa, Jr., W. B. Pardo, C. M. Ticos, J. Walkenstein, M. Monti,

                  Phase Synchronization of Chaos in a Plasma Discharge Tube

                  International Journal of Bifurcation and Chaos in Applied Sciences and Engineering 10, 2551 (2000).

F. Berttineto, C. M. Ticos, M.L. Pascu, C. Biloiu, Angela M. Dumitras,

                  Experimental Tunable Semiconductor Lasers,

                  Romanian Reports in Physics 49, 811 (1997).

E. Barna, V. Covlea, M. Bazavan, C. Biloiu, C. M. Ticos

                  Ionization Waves in the Medium Pressure Helium and Neon Plasma,

                  Fizika A 6, pp 131-138 (1997).

M.L. Pascu, B. Carstocea, G. Popescu, L. Gafencu, S. Apostol, N. Moise, M. Roman, C. M. Ticos,

                  Laser Method for Corneal Structure Investigation, Proc. SPIE Vol. 3405, p. 665 (1997).

G. Musa, I. Mustata, A. Popescu, G. Bajeu, C. M. Ticoš, A. Salabas, R. Breban, G.F. Leu, 

                  Preliminary Results on the Oscillatory Behavior of the Thermionic Vacuum Arc (TVA) in the Range of Negative Slope of the Current-Voltage        Characteristic,

                  Romanian Reports in Physics 48, 707 (1996).