- Email: [email protected]
Electrical discharges in air
Physics Letters A 306 (2002) 88–90 www.elsevier.com/locate/pla
Electrical discharges in air R. Antanasijevi´c a,∗ , R. Banjanac a , A. Dragi´c a , D. Jokovi´c a , D. Joksimovi´c a , Z. Mari´c a , B. Pani´c a , V. Udoviˇci´c a , J.P. Vigier b a Institute of Physics, PO Box 57, Belgrade 11001, Yugoslavia b CNRS/UPMC, URA 769, Gravitation et Cosmologie Relativistes, Tour 22-12, 4eme étage, Boîte 142, 4 Place Jussieu, 75005 Paris, France
Received 6 September 2002; received in revised form 21 October 2002; accepted 21 October 2002 Communicated by P.R. Holland
Abstract An experiment on electrical discharges in air under normal atmospheric conditions has been performed. The ratio between output and input energy is greater than 1, which confirms the results already reported by Graneau et al. 2002 Elsevier Science B.V. All rights reserved.
1. Introduction Recently, N. Graneau, P. Graneau and G. Hathaway [1] have published the results of a simple experiment consisting on electrical discharge in air, under the normal atmospheric conditions for an input energy in the interval of 100–500 J. The result is unexpected since the ratio of the output and input energies is greater than 1. This circumstance is intriguing and is the base for our motivation to repeat the experiment. At the same time in Graneau et al. report there are no precisions of the instruments used, in particular one does not find the experimental errors induced therefrom. Our experimental setup differs slightly from theirs in the following. We have not used the triggered arc gap because it is the source of the fluctuations and instability and we have changed the * Corresppnding author.
E-mail address: [email protected] (A. Dragi´c).
input energies by changing the arc gap distance. We are giving all the relevant characteristics of the instrument used.
2. Experimental setup The experimental setup is a simple electrical discharge circuit (Fig. 1). Capacitor C (manufactured by BICC, serial no. 340073; with declared capacitance of 3.75 µF/40 kV and measured capacitance of 3.9 ± 0.1 µF) gains electricity from high voltage power supply HV (voltage 0–20 kV). The spark gap is formed by two semispherical electrodes of half diameter d = 18 mm on distance that varies from 2 mm to 5 mm. In a series with the spark gap the resistance RL is connected (non-inductivity resistor of NiCr wire with a measured resistance of RL = 2.38 ± 0.01 ), which has been designed for current pulses intensities up to
0375-9601/02/$ – see front matter 2002 Elsevier Science B.V. All rights reserved. PII: S 0 3 7 5 - 9 6 0 1 ( 0 2 ) 0 1 4 9 6 - 2
R. Antanasijevi´c et al. / Physics Letters A 306 (2002) 88–90
89
Fig. 1. Schematic picture of the experimental device.
Fig. 2. Figure of typical oscilloscope signals.
60 kA and time 100 µs. The discharge current through the resistor RL is measured by a current transformer CT (Pearson Electronics inc., model No. 301X) with uncertainty of +1.5% and −0.5%, while resistor voltages uR and capacitor voltages uC are measured by high-voltage probes (type Tektronix P 6015A) with uncertainty of 1%. The obtained signals are digitized and analyzed by Tektronix TDS 540A oscilloscope. Typical signals are presented in the Fig. 2, where R1 represents the current i, R2 resistor voltage uR and R3 capacitor voltage uC . (Note: R2 and R3 graphs are shifted a little to the right not for physical reasons, but for better survey.)
3. Results The input (supplied) energy in the system is energy of capacitor discharge Win = 12 CUC2 . The Joule heat in the resistor RL is determined as Wout = RL i 2 dt, where i and t represent current through the resistor and time, respectively. Integration i 2 dt has been done numerically with a starting point of the time of beginning of the discharge. The discharge energy was obtained by changing the spark gap distance (from 2 to 5 mm). Relative ratio of Joule heat and input capacitor energy is denoted as Q = Wout /Win . Fig. 3 shows summarized results of Q versus input energy for every
90
R. Antanasijevi´c et al. / Physics Letters A 306 (2002) 88–90
higher. In order to (dis)prove the hypothesis in [1] that the excess energy is of molecular origin we intend: (1) to perform the experiment with the same setup by making discharges in argon, nitrogen and oxygen gases, and (2) to redo this experiment at lower pressures using variable arc gap distances and variable potentials. We believe that the experiments of such kind will help us to understand dynamics of the processes involved.
References Fig. 3. Relative ratio Q = Wout /Win vs. energy from the capacitor bank Win .
spark gap distance. These results are also compared with results of Graneau et al. [1].
4. Conclusion Our results confirm the reported energy excess and, as is seen from Fig. 3, are, for energies 100–400 J, even
[1] N. Graneau, P. Graneau, G. Hathaway, The electric air arc is an MHD generator, in: Proceedings of 36th Intersociety Energy Conversion Engineering Conference held in Savannah Georgia, July 29–August 2, 2001, p. 401.
Electrical discharges in air R. Antanasijevi´c a,∗ , R. Banjanac a , A. Dragi´c a , D. Jokovi´c a , D. Joksimovi´c a , Z. Mari´c a , B. Pani´c a , V. Udoviˇci´c a , J.P. Vigier b a Institute of Physics, PO Box 57, Belgrade 11001, Yugoslavia b CNRS/UPMC, URA 769, Gravitation et Cosmologie Relativistes, Tour 22-12, 4eme étage, Boîte 142, 4 Place Jussieu, 75005 Paris, France
Received 6 September 2002; received in revised form 21 October 2002; accepted 21 October 2002 Communicated by P.R. Holland
Abstract An experiment on electrical discharges in air under normal atmospheric conditions has been performed. The ratio between output and input energy is greater than 1, which confirms the results already reported by Graneau et al. 2002 Elsevier Science B.V. All rights reserved.
1. Introduction Recently, N. Graneau, P. Graneau and G. Hathaway [1] have published the results of a simple experiment consisting on electrical discharge in air, under the normal atmospheric conditions for an input energy in the interval of 100–500 J. The result is unexpected since the ratio of the output and input energies is greater than 1. This circumstance is intriguing and is the base for our motivation to repeat the experiment. At the same time in Graneau et al. report there are no precisions of the instruments used, in particular one does not find the experimental errors induced therefrom. Our experimental setup differs slightly from theirs in the following. We have not used the triggered arc gap because it is the source of the fluctuations and instability and we have changed the * Corresppnding author.
E-mail address: [email protected] (A. Dragi´c).
input energies by changing the arc gap distance. We are giving all the relevant characteristics of the instrument used.
2. Experimental setup The experimental setup is a simple electrical discharge circuit (Fig. 1). Capacitor C (manufactured by BICC, serial no. 340073; with declared capacitance of 3.75 µF/40 kV and measured capacitance of 3.9 ± 0.1 µF) gains electricity from high voltage power supply HV (voltage 0–20 kV). The spark gap is formed by two semispherical electrodes of half diameter d = 18 mm on distance that varies from 2 mm to 5 mm. In a series with the spark gap the resistance RL is connected (non-inductivity resistor of NiCr wire with a measured resistance of RL = 2.38 ± 0.01 ), which has been designed for current pulses intensities up to
0375-9601/02/$ – see front matter 2002 Elsevier Science B.V. All rights reserved. PII: S 0 3 7 5 - 9 6 0 1 ( 0 2 ) 0 1 4 9 6 - 2
R. Antanasijevi´c et al. / Physics Letters A 306 (2002) 88–90
89
Fig. 1. Schematic picture of the experimental device.
Fig. 2. Figure of typical oscilloscope signals.
60 kA and time 100 µs. The discharge current through the resistor RL is measured by a current transformer CT (Pearson Electronics inc., model No. 301X) with uncertainty of +1.5% and −0.5%, while resistor voltages uR and capacitor voltages uC are measured by high-voltage probes (type Tektronix P 6015A) with uncertainty of 1%. The obtained signals are digitized and analyzed by Tektronix TDS 540A oscilloscope. Typical signals are presented in the Fig. 2, where R1 represents the current i, R2 resistor voltage uR and R3 capacitor voltage uC . (Note: R2 and R3 graphs are shifted a little to the right not for physical reasons, but for better survey.)
3. Results The input (supplied) energy in the system is energy of capacitor discharge Win = 12 CUC2 . The Joule heat in the resistor RL is determined as Wout = RL i 2 dt, where i and t represent current through the resistor and time, respectively. Integration i 2 dt has been done numerically with a starting point of the time of beginning of the discharge. The discharge energy was obtained by changing the spark gap distance (from 2 to 5 mm). Relative ratio of Joule heat and input capacitor energy is denoted as Q = Wout /Win . Fig. 3 shows summarized results of Q versus input energy for every
90
R. Antanasijevi´c et al. / Physics Letters A 306 (2002) 88–90
higher. In order to (dis)prove the hypothesis in [1] that the excess energy is of molecular origin we intend: (1) to perform the experiment with the same setup by making discharges in argon, nitrogen and oxygen gases, and (2) to redo this experiment at lower pressures using variable arc gap distances and variable potentials. We believe that the experiments of such kind will help us to understand dynamics of the processes involved.
References Fig. 3. Relative ratio Q = Wout /Win vs. energy from the capacitor bank Win .
spark gap distance. These results are also compared with results of Graneau et al. [1].
4. Conclusion Our results confirm the reported energy excess and, as is seen from Fig. 3, are, for energies 100–400 J, even
[1] N. Graneau, P. Graneau, G. Hathaway, The electric air arc is an MHD generator, in: Proceedings of 36th Intersociety Energy Conversion Engineering Conference held in Savannah Georgia, July 29–August 2, 2001, p. 401.