measuring x-ray emission from lightning - stanford university• lightning is exotic kind of...
TRANSCRIPT
![Page 1: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/1.jpg)
Measuring x-ray emission from
lightning
Joseph R. DwyerDepartment of Physics and Space Sciences
Florida Institute of Technology
![Page 2: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/2.jpg)
Other people involved in this research
H. K. Rassoul, Z. Saleh, M. Al-Dayeh, D. Concha, M. Bakhtiari,S. Lazarus, and M. Splitt
Florida Institute of Technology
M. A. Uman, V. A. Rakov, J. Jerauld, D. M. Jordan, K. J. Rambo, and J. HowardUniversity of Florida, Gainesville
D. M. Smith University of California, Santa Cruz
J. A. PlumerLightning Technologies Inc., Pittsfield, MA
![Page 3: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/3.jpg)
Despite its familiarity, lightning remains a mystery
• Big question #1: What microphysical processes are responsible for thunderstorm electrification?
• Big question #2: How does lightning get started with the relatively low electric field strengths inside thunderstorms?
• Big question #3: How does lightning travel through tens of kilometers of air?
![Page 4: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/4.jpg)
Since we are still struggling to understand how lightning works250 years after Franklin’s kite experiment, perhaps we are
missing something important….
Runaway Electrons
![Page 5: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/5.jpg)
25 MeV electron moving through air at 1 atm
![Page 6: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/6.jpg)
25 MeV electron moving through air at 1 atmin a 3 kV/cm electric field
![Page 7: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/7.jpg)
Energy loss and gain experienced by an electron in air
![Page 8: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/8.jpg)
Relativistic Breakdown due to x-ray and positron feedback.
The central avalanche is due to the injection of a single, 1 MeV seed electron. All the other avalanches are produced by x-ray and positron feedback. The top panel is for times, t < 0.5 μs. The middle panel is fort < 2 μs, and the bottom panel is for t < 10 μs.
![Page 9: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/9.jpg)
Gamma-ray bursts seen from spaceBATSE Terrestrial Gamma-ray Flash (TGF)
![Page 10: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/10.jpg)
BATSE Terrestrial Gamma-ray Flash (TGF)
![Page 11: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/11.jpg)
Terrestrial Gamma-Ray Flash (TGF) spectrum and results of Monte Carlo simulation for different source altitudes
![Page 12: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/12.jpg)
What about lightning?
Experiment Location X-rays in thunderstorms?
X-rays inlightning?
Appleton & Bowen (1933) ground No No
Macky (1934) balloon No No
Clay et al. (1952) ground Yes No
Hill (1963) 300 m tower No No
McCarthy & Parks (1985) aircraft Yes No
Fishman et al. (1994) space ? No
Moore et al. (2001) mountain (3288 m) No Yes
![Page 13: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/13.jpg)
Rocket-triggered lightning
![Page 14: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/14.jpg)
Instrument used to measure x-rays from lightning at the UF/Florida Tech International Center for Lightning Research and
Testing (ICLRT) at Camp Blanding, FL
![Page 15: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/15.jpg)
Instrument configuration with collimators
![Page 16: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/16.jpg)
Data acquisition is triggered using current measurements for triggered lightning and optical measurements for natural lightning.
For each trigger, the signals from the PMT anodes are recorded for2 seconds (0.5 sec pre-trigger data) with 0.1 μsec resolution.
![Page 17: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/17.jpg)
An x-ray instrument at the ICLRT
![Page 18: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/18.jpg)
X-ray instruments in front of rocket launch towerused to trigger lightning
![Page 19: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/19.jpg)
Rocket-triggered lightning
![Page 20: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/20.jpg)
Rocket-triggered lightning
![Page 21: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/21.jpg)
Rocket-triggered lightning
![Page 22: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/22.jpg)
Triggering lightningMethod 2
![Page 23: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/23.jpg)
X-rays from rocket-triggered lightning dart leaders
![Page 24: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/24.jpg)
Energy of x-rays from triggered lightning
![Page 25: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/25.jpg)
X-rays from natural cloud-to-ground lightning
![Page 26: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/26.jpg)
![Page 27: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/27.jpg)
Thunderstorm Energetic Radiation Array (TERA)
• With funding from a NSF/MRI grant, we are currently constructing 32 new x-ray instruments, each containing two 3”NaI(Tl)/PMT detectors, covering 1 square km at the ICLRT.
• For the summer of 2006 we had the first twenty elements in placeplus four old instruments. The remainder of the array will be added over the next year.
• At the TERA stations we also make electric and magnetic field, fast dE/dt and optical measurements. In addition, will have current measurements for triggered lightning.
• TERA will make detailed measurements of x-ray emission from natural and triggered lightning and thunderstorms.
![Page 28: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/28.jpg)
TERA at the UF/Florida Tech International Center for Lightning Research and Testing (ICLRT) at Camp Blanding, FL
![Page 29: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/29.jpg)
TERA Instrument Design
![Page 30: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/30.jpg)
Natural Lightning Data on 09/28/05Negative Cloud-to-Ground
![Page 31: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/31.jpg)
Natural lightning strike as measured by TERA station 1
![Page 32: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/32.jpg)
Close-up view
![Page 33: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/33.jpg)
Response Fit
![Page 34: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/34.jpg)
Response Fit
![Page 35: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/35.jpg)
Response Fit
![Page 36: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/36.jpg)
First energy spectra of x-rays from lightning
1/E
![Page 37: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/37.jpg)
Pulse Time DistributionC
ount
![Page 38: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/38.jpg)
TERA 2, 4, 7 & 10 for the event 08/28/05
T 2
T 7
T 4
T 10
![Page 39: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/39.jpg)
Individual Energy Spectrum for TERA 2, 4, 7 & 10 for the event 08/28/05
TERA 4
TERA 2
TERA 7
TERA 10
1/E
![Page 40: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/40.jpg)
2 m spark produced by a 1.5 MV Marx generator
![Page 41: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/41.jpg)
X-ray emission from laboratory sparksX-rays bursts occurred during discharges
from a 1.5 MV Marx generator
![Page 42: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/42.jpg)
No x-rays were detected from the world’s largest air insulated Van de Graaff machine at the Boston Museum of Science
![Page 43: Measuring x-ray emission from lightning - Stanford University• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of](https://reader033.vdocuments.us/reader033/viewer/2022042007/5e706aa64d3750252c229cfd/html5/thumbnails/43.jpg)
Conclusions
• Lightning is exotic kind of discharge that involves runaway electrons, which are accelerated to nearly the speed of light and produce large numbers of x-rays.
• Since the standard models of lightning do not include runaway electrons nor do they predict x-ray emission, clearly we need to revisit these models.
• X-rays give us a new tool for studying lightning.
• The Thunderstorm Energetic Radiation Array (TERA) at Camp Blanding, FL is currently giving us a new way of looking at lightning.