On the possible origin of X-rays in long laboratory sparks

Cooray, Vernon; Arévalo, Liliana; Rahman, Mahbubur; Dwyer, J. R.; Rassoul, H. K.

doi:10.1016/j.jastp.2009.07.010

Cited by 50 publications

(63 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It has been found that RF radiation power at ∼2.4 GHz is correlated with the emission of X-rays from a long spark (Montanyà et al, 2015). It has been suggested that extremely strong electric field that is required for X-ray production during spark discharges was produced by the head-on collisions of streamers (e.g., Cooray et al, 2009;Kochkin et al, 2012). However, theoretical studies have indicated that the head-on collision of streamers is unlikely to produce significant emissions of X-rays because the enhanced electric field due to collision collapses on a very short timescale of a few picoseconds (Babich & Bochkov, 2017;Ihaddadene & Celestin, 2015;Köhn et al, 2017).…”

Section: 1029/2018gl080309mentioning

confidence: 99%

VHF and UHF Electromagnetic Radiation Produced by Streamers in Lightning

Shi

Liu

Dwyer

et al. 2019

Geophysical Research Letters

View full text Add to dashboard Cite

In this letter, we report simulation results of streamer propagation and collision that produce electromagnetic radiation in the very high frequency (VHF) and ultra high frequency (UHF) bands. The streamers are initiated in overbreakdown field conditions, 1.5Ekand2Ek, respectively, which may be found during the corona flash stage of negative leader stepping processes. We find that while streamer propagation produces stronger VHF radiation, the head‐on collision of streamers dominates UHF, and even higher‐frequency radiation. Analysis of the energy spectral densities obtained from different simulation cases shows that the total length and radii of colliding streamers, as well as the ambient field, are important parameters for the UHF radiation produced by streamer collisions. The larger those parameters are, the stronger UHF radiation produced. Finally, by comparing with the measured spectral magnitude of lightning field in the VHF range, it is found that there are probably 105–107 streamers involved during the lightning corona flash stage.

show abstract

Section: 1029/2018gl080309mentioning

confidence: 99%

VHF and UHF Electromagnetic Radiation Produced by Streamers in Lightning

Shi

Liu

Dwyer

et al. 2019

Geophysical Research Letters

View full text Add to dashboard Cite

show abstract

“…The exact mechanism that leads to the generation of X-rays in laboratory sparks is still under investigation. It has been suggested, however, that the field enhancements caused during streamer encounters could be one possible mechanism that generates X-rays (Cooray et al [8]). During these encounters, electrons could be accelerated beyond the threshold energies necessary for them to become runaways in the lower background fields.…”

Section: Introductionmentioning

confidence: 99%

Energy Distribution of X-rays Produced by Meter-Long Negative Discharges in Air

et al. 2017

Self Cite

View full text Add to dashboard Cite

Abstract:The energy deposited from X-rays generated by 1 m long laboratory sparks in air created by 950 kV negative lightning impulses on scintillated detectors was measured. Assuming the X-ray energy detected in such sparks results from the accumulation of multiple photons at the detector having a certain energy distribution, an experiment was designed in such a way to characterize their distribution parameters. The detector was screened by a copper shield, and eight series of fifteen impulses were applied by stepwise increasing the copper shield thickness. The average deposited energy was calculated in each series and compared with the results from a model consisting of the attenuation of photons along their path and probable photon distributions. The results show that the energy distribution of X-ray bursts can be approximated by a bremsstrahlung spectrum of photons, having a maximum energy of 200 keV to 250 keV and a mean photon energy around 52 keV to 55 keV.

show abstract

“…X-rays can also occur during the initiation of sparks in the laboratory on a scale of millimetres up to metres, even with standard atmospheric conditions of approximately 1 bar and 20 • C. Unrolling adhesive tapes generates x-rays [9], as do helium-filled spark chambers [10], the formation of corona discharges [11] on a centimetre scale, or metre long discharges [12][13][14][15]. X-rays are a common feature of a high-voltage (HV) discharge, regardless of size.…”

Section: Introductionmentioning

confidence: 99%

Experimental study of hard x-rays emitted from metre-scale positive discharges in air

Kochkin¹,

Nguyen²,

Deursen³

et al. 2012

J. Phys. D: Appl. Phys.

104

138

View full text Add to dashboard Cite

We investigate structure and evolution of long positive spark breakdown; and we study at which stage pulses of hard X-rays are emitted. Positive high-voltage pulses of standardized lightning impulse wave form of about 1 MV were applied to about 1 meter of ambient air. The discharge evolution was imaged with a resolution of tens of nanoseconds with an intensified CCD camera. LaBr 3 (Ce + ) scintillation detectors recorded the X-rays emitted during the process. The voltage and the currents on both electrodes were measured synchronously. All measurements indicate that first a large and dense corona of positive streamers emerges from the high voltage electrode. When they approach the grounded electrode, negative counter-streamers emerge there, and the emission of hard X-rays coincides with the connection of the positive streamers with the negative counter-streamers. Leaders are seen to form only at later stages.

show abstract

On the possible origin of X-rays in long laboratory sparks

Cited by 50 publications

References 13 publications

VHF and UHF Electromagnetic Radiation Produced by Streamers in Lightning

VHF and UHF Electromagnetic Radiation Produced by Streamers in Lightning

Energy Distribution of X-rays Produced by Meter-Long Negative Discharges in Air

Experimental study of hard x-rays emitted from metre-scale positive discharges in air

Contact Info

Product

Resources

About