Thunderbolts Forum v3.0

by **Michael Mozina** » Thu Dec 31, 2020 12:44 am

Higgsy wrote: ↑Wed Dec 30, 2020 11:48 pm
Higgsy wrote: ↑Mon Dec 28, 2020 3:53 pm
Cargo wrote: ↑Mon Dec 28, 2020 7:03 am Higgs, how are you measuring "density"?
So far as density in the corona goes, the temperature is measured by spectroscopy and the density is determined by multi-colour photometry and polarimetry. See: Dudik et al, Electron Densities in the Solar Corona Measured Simultaneously in the Extreme-Ultraviolet and Infra-Red, https://arxiv.org/abs/2011.09175; or Del Zanna and Mason, Solar UV and X-ray spectral diagnostics, Living Rev Sol Phys 15, 5 (2018).
There's also: Harry P. Warren and David H. Brooks , The temperature and density structure of the solar corona, 2009 ApJ 700 762, available here
and Young et al High-precision density measurements in the solar corona, A&A 495, 587–606 (2009), here

It should be noted that most of the higher energy lines associated highly ionized Iron and Silicon occur inside of "coronal loops","magnetic ropes", 'Birkeland currents", whatever you wish to call them. The *electrical current* flowing through them, and resistance to that currents, sustains the plasma at these high temperatures. The sun's corona also scatters the light around from their emissions points. The whole corona doesn't have to actually be 1MK, but the average coronal loop, even during 'quiet" periods is approximately 1MK.

by **Higgsy** » Wed Dec 30, 2020 11:48 pm

Higgsy wrote: ↑Mon Dec 28, 2020 3:53 pm
Cargo wrote: ↑Mon Dec 28, 2020 7:03 am Higgs, how are you measuring "density"?
So far as density in the corona goes, the temperature is measured by spectroscopy and the density is determined by multi-colour photometry and polarimetry. See: Dudik et al, Electron Densities in the Solar Corona Measured Simultaneously in the Extreme-Ultraviolet and Infra-Red, https://arxiv.org/abs/2011.09175; or Del Zanna and Mason, Solar UV and X-ray spectral diagnostics, Living Rev Sol Phys 15, 5 (2018).

There's also: Harry P. Warren and David H. Brooks , The temperature and density structure of the solar corona, 2009 ApJ 700 762, available here
and Young et al High-precision density measurements in the solar corona, A&A 495, 587–606 (2009), here

by **Higgsy** » Tue Dec 29, 2020 1:28 pm

paladin17 wrote: ↑Mon Dec 28, 2020 6:54 pm I would like to point out Robitaille's idea that the ionization in the corona may be not thermal (or at least not only thermal), but rather chemical in nature (arising from high electron affinity of [hypothetical?] hydrogen clusters present there that strip other elements of their electrons), and therefore the measurements of temperature inferred from it are flawed. Whether he is right or wrong I cannot say, as I haven't studied the question enough, but the idea looks pretty elegant to me, as it removes the "heating problem" entirely.

I am entirely unconvinced by Robitaille's proposal from the very first step in his chain of logic where he misunderstands Kirchoff's law to apply only to condensed matter, and wrongly claims that thermal radiation cannot be emitted by a highly ionised Maxwellian gas, through pretty much every step of his logic. With regard to the specific claim you refer to, it seems to be an entirely hand-waving suggestion. He doesn't explain how hydrogen can exist in the liquid metallic state in the conditions of the corona (even if the corona temperature is "only" a few thousand K and at a hydrostatic pressure commensurate with the boundary condition of effectively zero pressure), he doesn't make any claim for the electron affinity and electro-negativity of liquid metallic hydrogen, and he doesn't explain how this chemical process can strip electrons to Fe-XIV and beyond at a detectable rate. Just because he wrote down a reaction doesn't mean that that reaction will happen at a detectable rate (or at all). (Robitaille, Pierre-Marie. (2013). The Liquid Metallic Hydrogen Model of the Sun and the Solar Atmosphere V. On the Nature of the Corona. Progress in Physics. 3. L22-L25. available in ResearchGate )

When he writes in what is supposed to be a formal scientific paper: "Today, the situation has changed dramatically, as a great deal of evidence is building that the Sun is condensed matter (see [2,24,27–30] and references therein)", and you realise [2,24,27–30] are all self-references, alarm bells ring.

by **paladin17** » Mon Dec 28, 2020 6:54 pm

Higgsy wrote: ↑Mon Dec 28, 2020 3:15 pm By the unusual spectrum, I assume you mean the unexplained dip in gamma.

Of course.

Higgsy wrote: ↑Mon Dec 28, 2020 3:53 pm So far as density in the corona goes, the temperature is measured by spectroscopy

I would like to point out Robitaille's idea that the ionization in the corona may be not thermal (or at least not only thermal), but rather chemical in nature (arising from high electron affinity of [hypothetical?] hydrogen clusters present there that strip other elements of their electrons), and therefore the measurements of temperature inferred from it are flawed. Whether he is right or wrong I cannot say, as I haven't studied the question enough, but the idea looks pretty elegant to me, as it removes the "heating problem" entirely.

Higgsy wrote: ↑Mon Dec 28, 2020 5:56 pm By the way, aren’t the GeV gamma supposedly something to do with cosmic ray interaction?

Supposedly. But the papers I saw on the topic (in early 2019) claimed that there is yet no working model of how they would generate the observed spectra/long-term dynamics. It is kinda obvious that cosmic rays would be the first suspect simply due to their energy, but what else is at work there - we don't quite know. I would assume there are already a few dozens of papers (if not more - I may be too optimistic) on arXiv invoking new physics to explain that.

by **Higgsy** » Mon Dec 28, 2020 5:56 pm

Higgsy wrote: ↑Mon Dec 28, 2020 3:15 pm
paladin17 wrote: ↑Mon Dec 28, 2020 8:04 am
Higgsy wrote: ↑Mon Dec 28, 2020 12:56 am This woud be an explanation for the gamma production, the abundance of 3He and the positron annihilation signature in the corona, particukarly at flares.
There's still a problem of GeV range gammas. And the curious dependence of their emission on the cycle phase (more high energy photons at minimum, and from the equatorial region of all places), as well as their unusual spectrum.
Indeed, these things are problems needing solutions, and I don't claim that my laborious calculation (done partly as a demonstration to people of how to do order of magnitude sanity checks, in the hope that they'll do more themselves) answers any of them. It merely confirms that some low level of pp fusion can take place in the corona, that the level is quite insignificant as a contribution to the solar energy ouput, but that some measurable 3He and 0.511MeV photons could result. Presumably the 0.511MeV photon intensity could give a measure of pp fusion rate at various places with some assumptions. By the unusual spectrum, I assume you mean the unexplained dip in gamma.

By the way, aren’t the GeV gamma supposedly something to do with cosmic ray interaction?

by **Higgsy** » Mon Dec 28, 2020 3:53 pm

Cargo wrote: ↑Mon Dec 28, 2020 7:03 am Higgs, how are you measuring "density"?

So far as density in the corona goes, the temperature is measured by spectroscopy and the density is determined by multi-colour photometry and polarimetry. See: Dudik et al, Electron Densities in the Solar Corona Measured Simultaneously in the Extreme-Ultraviolet and Infra-Red, https://arxiv.org/abs/2011.09175; or Del Zanna and Mason, Solar UV and X-ray spectral diagnostics, Living Rev Sol Phys 15, 5 (2018).
So far as density in the centre goes it is inferred from the state of hydrostatic and thermodynamic equilibrium via gas laws and the virial theorem and a set of (seven) differential equations which make use of measured properties such as solar mass, diameter, luminosity, and so on. The theory can be found in all good solar textbooks.

by **Higgsy** » Mon Dec 28, 2020 3:15 pm

paladin17 wrote: ↑Mon Dec 28, 2020 8:04 am
Higgsy wrote: ↑Mon Dec 28, 2020 12:56 am This woud be an explanation for the gamma production, the abundance of 3He and the positron annihilation signature in the corona, particukarly at flares.
There's still a problem of GeV range gammas. And the curious dependence of their emission on the cycle phase (more high energy photons at minimum, and from the equatorial region of all places), as well as their unusual spectrum.

Indeed, these things are problems needing solutions, and I don't claim that my laborious calculation (done partly as a demonstration to people of how to do order of magnitude sanity checks, in the hope that they'll do more themselves) answers any of them. It merely confirms that some low level of pp fusion can take place in the corona, that the level is quite insignificant as a contribution to the solar energy ouput, but that some measurable 3He and 0.511MeV photons could result. Presumably the 0.511MeV photon intensity could give a measure of pp fusion rate at various places with some assumptions. By the unusual spectrum, I assume you mean the unexplained dip in gamma.

by **paladin17** » Mon Dec 28, 2020 8:04 am

Higgsy wrote: ↑Mon Dec 28, 2020 12:56 am This woud be an explanation for the gamma production, the abundance of 3He and the positron annihilation signature in the corona, particukarly at flares.

There's still a problem of GeV range gammas. And the curious dependence of their emission on the cycle phase (more high energy photons at minimum, and from the equatorial region of all places), as well as their unusual spectrum.

by **Cargo** » Mon Dec 28, 2020 7:03 am

Higgs, how are you measuring "density"?

by **Higgsy** » Mon Dec 28, 2020 12:56 am

On Dec 22nd I said I'd do some sums to estimate the reaction rates in the corona, so here we go. There are many simplifying assumptions (eg I only consider PP I chain, not PP II, PP III or CN), however the orders of magnitude will not be too far off.

The first step of the pp chain is mediated by the weak force and so does not occur readily but once it occurs the deuterium product of the first step will readily react with a proton to form 3He.

Looking at the core of the Sun, say, within ~0.3 solar radius:
Radius of core = 1.75 x 10^8 m
Volume of core = 2.24 x 10^25 m^3
Power output of core 3.9 x 10^26 W
Average density of power output = 17 W.m^-3
But the power output is greatest at the centre and falls to near zero on the edge of the core, so in the centre we can estimate a rate at least 10x the average: 170 W.m^-3
Each pp reaction to 4He releases ~25MeV of energy = 4 x 10^-12 J
Therefore the reaction rate for the first step in the centre is 2 x 4.25 x 10^13 m^-3.s^-1 = 8.5 x 10^13 m^-3.s^-1 (It takes two first step reactions to end in one 4He)

The reaction rate goes as the fourth power of temperature (at least in the temperature region we are interested i), and as the particle density.

The temperature in the centre = 1.5 x 10^7 K
The temperature in the quiet corona = 1 x 10^6 K and in the active corona 3 x 10^6 K. Let's take the latter.
The coronal reaction rate is thus 625 times less than the core on the basis of temperature.

The density in the centre is 1.5 x 10^5 kg.m^-3 of which one in ten nucleons is a unbound proton. So the density of protons is 1.5 x 10^4 kg.m^-3 or 9.4 x 10^30 protons m^-3.
The density in the corona is 10^15 protons m^-3.
The coronal reaction rate goes as (9.4 x 10^30/10^15) = 9.4 x 10^15 times less than in the core on the basis of density.

Therefore, the total rate in the corona is 5.9 x 10^18 less than in the core.

Thus the rate of pp reactions in the corona is 8.5 x 10^13/5.9 x 10^18 = 1.4 x 10^-5 s^-1.m^-3.

If we estimate the depth of the corona to be 50,000km (density drops by almost an order of magnitude by 70,000km) or 5 x 10^7m then its volume is 3.2 x 10^26 m^3 (this is generous as the corona becomes less dense, resulting in lower reaction rate with distance above the surface).

The total pp reactions in the entire corona would therefore be 3.2 x 10^26 x 1.4 x 10^-5 = 4.5 x 10^21 s^-1.
A complete pp chain through all three steps to 4He releases ~25MeV, but in the corona, the last reaction in the pp chain (3He + 3He > 4He + 1p + 1p + 12.8MeV) is unlikely because of the low density of 3He, so each pp chain stops after step 2 (the proton deuterium fusion) and results in a total 6.9MeV or 1.1 x 10^-12J.

The power from the pp chain in the entire corona is therefore ~4.5 x 10^21 x 1.1 x10^-12 = 5 x 10^9W (number of reactions per second times energy per reaction). So fusion in the corona is a completely insignificant part of the Sun's power output.

The power density in the corona is 1.4 x 10^-5 x 1.1 x 10^-12 = 1.5 x 10^-17 W.m^-3 (reactions per second per cubic meter times energy per reaction).

There is an interesting paper which proposes fusion in coronal flares: Ying-Zhi Zhang 2020 Res. Astron. Astrophys. 20 026, https://arxiv.org/pdf/1912.00193.pdf. He models a coronal flare using MHD and then calculates the fusion rate and the contribution of fusion to the heating of the flare. He comes up with a energy production of 3 x 10^-7 J.m^-3 and a total production of 27,000 m^-3 reactions in an event that lasts 9,900s. That is equivalent to 10^-11W.m^-3, which is 6.7 x 10^5 times greater than the number I came up with above as an average for the entire corona. His modelling indicates that the centre of the flare will average over time about 2 x 10^7K and have a density of 1.25 x 10^16 particles m^-3 (cf my assumptions for the average across the corona are 3 x 10^6K and 10^15 particles m^-3 which taken together give a factor in reaction rate of 2.5 x 10^4, so we agree within an order of magnitude or so).

This woud be an explanation for the gamma production, the abundance of 3He and the positron annihilation signature in the corona, particukarly at flares.

by **Solar** » Sat Dec 26, 2020 10:26 pm

Using a CCD camera sensitive to 300-700 nm this team recorded airglow fluorescence of air molecules excited by the Runaway Relativistic Electron Avalanche (RREA) dynamic billed as "the first optical signature of RREA developed in the lower part of the thundercloud" A link is provided to the all sky videos of the recordings.

Despite its simplicity it was a little difficult to follow without referring back and forth to the dynamics portrayed in Fig 1. Figure 1 in this paper treats the thundercloud as a vertical dipole. Most of the document covers measurements related to the lower half of the vertical dipole. This means that the reader has to first split the dipole into upper and lower regions. The middle of the dipole is labeled MN: main negative charge region.

Then, split the lower half of the dipole into two regions again. So, between the middle negative charge region and the surface of the Earth the reader will have:

MN: main negative charge region
LPCR: “emerging lower positively charged layer
TGE: Thunderstorm Ground Enhancements

The red vertical arrows refer to the E-Field vectors for the various regions, the small green clouds in the lower right-hand corner refer to enhancement of naturally occurring gamma radiation from randon progenies which can become airborn due to E-Field. The authors are depicting gamma ray, neutrons, and positron emission both above and below the middle negative charge region (MN).

ABSTRACT
Natural gamma radiation (NGR), one of the major geophysical parameters directly connected with cloud electrification and lightning initiation, is highly enhanced during thunderstorms. At low energies below 3 MeV, the enhancement of NGR is due to natural isotope radiation, and for energies up to 50 MeV, it is due to the operation of the newly discovered electron accelerators in the thunderclouds. For the first time, we present a comprehensive model of the enhanced fluxes of radiation incident on the earth's surface during thunderstorms. In addition to the already explained minute-long fluxes of high-energy electrons and gamma rays from relativistic runaway electron avalanches (RREA), we clarify also the origin of hour-long isotropic fluxes of low-energy gamma rays from the Rn-222 progenies. Also, as a direct evidence of RREA, we present photographs of optical emission during the development of electron-gamma ray cascades in the atmosphere. Natural radioactivity is a source of continuous exposure of human beings to radiation. Radiation protection of living organisms requires an understanding of all sources and possible ways of enhancement of the radiation levels that can double for several hours in the energy domain of hundreds of keV. Therefore individual irradiation doses can be exceeded during thunderstorms. The models used for the forecasting of thunderstorms and other severe atmospheric phenomena need an accurate account of the ionizing radiation in the atmosphere. The airglows can influence the operation of optical, fluorescence, and atmospheric Cherenkov telescopes and fluorescence detectors. - Origin of enhanced gamma radiation in thunderclouds: A. Chilingarian, G. Hovsepyan, A. Elbekian et al, 11 December 2019

I've read your interesting advise Higgsy.

by **Higgsy** » Tue Dec 22, 2020 5:58 pm

Solar wrote: ↑Mon Dec 21, 2020 5:41 pm Per this next short Open Access lightning research paper the detection of “neutron capture” by hydrogen nuclei (protons) in the scintillator which released the characteristic gamma ray signature at 2.223 MeV accompanied by the formation of … deuterium.
...
Along with the 511 keV annihilation line, as well as neutron emission, the 2.223 MeV signature of neutron capture may also be present. Both have been detected with terrestrial lightning. Interestingly, both emission lines have also been detected at the Sun during solar flares. Here is brief mention of this observation:

This is interesting as I said before. From the various papers you have linked to I am particularly interested in the detection of positron annihilation and the neutron capture in terrestrial lightning strikes. Of course, we have to be circumspect in drawing parallels between those and solar flares, especially as the coronal density is some 10^13 times less than atmospheric density.

Here also, is what must be the shortest paper I’ve ever seen. The paper was open access when I visited:

Notice the interesting reference to “the narrow deuterium line”. Notice also what the document refers to as the “possibility” that electrons and ions might be accelerated in different directions via DC electric field. Moreover, might there be comparison made with regard to this “delayed” 2.223 MeV emission which apparently occurred after the emission of “prompt” gamma rays occurring ~10s after the electron bremsstrahlung? (Fig 1).

This is a very early imaging of a solar flare in keV to MeV (hard X-ray to gamma ray) energies. There must be more recent appers but I haven't time to look for them now. The signature of neutron capture to form deuterium is not unexpected. Since deuterium will be vanishingly sparse compared with protons in the corona, deuterium-deuterium reactions are unlikely, but the possibility of deuterium-proton to form 3He is possible, I suppose. I think I should do some sums to estimate the likely reaction rates in the corona, but that will have to wait for a few days.

Regarding the length of the paper - I think it is published in conference proceedings, so it is possibly a summary of conference paper. OT, but the shortest high impact paper that I am aware of is Watson and Crick's 1953 Nature publication of the structure of DNA.

Might the linear ‘timing’ of 511 keV and "delayed" 2.223 MeV in solar flare phenomena have relevance to the linear timing of terrestrial lightning? The timing of events is something that lightning research efforts are trying to decipher. These same signatures manifesting at the sun might make for interesting comparison along that line of reasoning.

Perhaps, but the conditions are so different, from density to temperature to elements present, that caution is called for.

by **Solar** » Mon Dec 21, 2020 5:41 pm

Per this next short Open Access lightning research paper the detection of “neutron capture” by hydrogen nuclei (protons) in the scintillator which released the characteristic gamma ray signature at 2.223 MeV accompanied by the formation of … deuterium.

Following a lightning strike to a wind turbine in Japan, we have observed a large burst of
neutrons lasting 100 ms with a ground fluence of ~1,000 n cm2, thousands of times greater than the peak neutron flux associated with the largest ground level solar particle event ever observed. This is the first detection of an unequivocal signature of neutrons from a terrestrial gamma ray flash, consisting of a 2.223 MeV gamma-ray spectral line from a neutron-capture on hydrogen reaction occurring in our detector, and is shown to be consistent with the production of 1012–1013 photoneutrons from a downward terrestrial gamma ray flash (TGF) at 1.0 km, with a gamma ray brightness typical of upward TGFs observed by satellites. - Gamma Ray Signatures of Neutrons From a Terrestrial Gamma Ray Flash - G. S. Bowers1 , D. M. Smith , G. F. Martinez-McKinney et al 2017

Along with the 511 keV annihilation line, as well as neutron emission, the 2.223 MeV signature of neutron capture may also be present. Both have been detected with terrestrial lightning. Interestingly, both emission lines have also been detected at the Sun during solar flares. Here is brief mention of this observation:

RHESSI Observes 2.2 MeV Line Emission from a Solar Flare

Here also, is what must be the shortest paper I’ve ever seen. The paper was open access when I visited:

We present the first gamma-ray images of a solar ﬂare, obtained with the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) for the X4.8 ﬂare of 2002 July 23. Two rotating modulation collimators (35 & 180 resolution) provided images of the narrow deuterium line at 2.223 MeV formed by thermalization and capture of neutrons produced in energetic ion collisions, the 3.25-6.5 MeV band that includes the prompt de-excitation lines of C and O, and the 0.3 - 0.5 and 0.7-1.4 MeV bands that are dominated by electron-bremsstrahlung. The centroid of the 2.223 MeV image was found to be displaced by ∼20(±6) arcsec from that of the 0.3-0.5 MeV band, implying a difference in acceleration and/or propagation between the accelerated electron and ion populations near the Sun. - First Gamma-Ray Images of a Solar Flare - G. J. Hurford, R. A. Schwartz, S. Krucker et al 2008

Notice the interesting reference to “the narrow deuterium line”. Notice also what the document refers to as the “possibility” that electrons and ions might be accelerated in different directions via DC electric field. Moreover, might there be comparison made with regard to this “delayed” 2.223 MeV emission which apparently occurred after the emission of “prompt” gamma rays occurring ~10s after the electron bremsstrahlung? (Fig 1).

Might the linear ‘timing’ of 511 keV and "delayed" 2.223 MeV in solar flare phenomena have relevance to the linear timing of terrestrial lightning? The timing of events is something that lightning research efforts are trying to decipher. These same signatures manifesting at the sun might make for interesting comparison along that line of reasoning.
_________

Lastly, here is an example of the precursor glow phase occurring before the manifestation of the actual discharge (and also "abruptly terminating" afterward). The glow may have been the result of a "current pulse" - it may have been precursor ionization necessary in providing electrons for the subsequent discharge, or both. As expressed elsewhere I am very interested in the manifestation called "Bipolar Bidirectional Leader". When watching this next video click the cog in the lower right hand corner and select "Playback speed". Set to 0.25 (slowest). This will allow you to pause at approximately 0.13 seconds and observe not only the progression of the preceding glow but also the appearance of the bidirectional leader at some distance below the glow in less dense "virgin air" and at what may be an interface, or boundary, between different atmospheric 'layers':

A Sprite in Action

by **Solar** » Tue Dec 08, 2020 9:25 pm

Also: The main longstanding theory behind the acceleration of electrons via electric field in thunderstorms accompanied Bremsstrahlung (“breaking” radiation) when those accelerated electrons decelerate as a result of interacting with air molecules) is Relativistic Runaway Electron Avalanche (RREA) or Runaway Breakdown (RB):

A moment of recognition is warranted for the work of C. T. R. Wilson who not only put forth the concept of “runaway” electrons with regard to lightning in 1925, he also put forth “The Global Atmospheric Electrical Circuit”, he apparently predicted sprites in the middle atmosphere, he shared half of the 1927 Nobel Prize with A. H. Compton, and he invented the Cloud Chamber which was used to discover the Positron amongst other things.

Some sixty years after Wilson’s 1925 paper suggesting “runaway” electrons Gurevich et al. [1992] and Gurevich and Zybin [2001] put forth their version with Wilson’s work forming the foundation of same. That is the origin of what is now called Relativistic Runaway Electron Avalanche (RREA).

Point of fact the upward and downward positive and negative ‘vertical currents’ associated with the GEC are called “Wilson Currents”. Out of curiosity I put “Wilson” into the respective search engines of Thunderbolts main website and Holoscience - Mr. Wilson’ work is briefly mentioned on only one Holoscience page.

Here is brief history of Mr. Wilson:

The cloud chamber and CTR Wilson’s legacy to atmospheric science

The Cloud Chamber: Hyperphysics

C.T.R. Wilson Nobel Lecture December 12, 1927: On the Cloud Method of Making Visible Ions and the Tracks of Ionizing Particles

For some reason its fascinating that when theorizing about the interaction of photons with atoms and electrons it were theorized that the interaction might induce the electron to "recoil". As A. H Compton noted in his own Nobel Lecture:

When this theory was first proposed, no electrons of this type were known; but they were discovered by Wilson and Bothe within a few months after their prediction. - Arthur H. Compton: X-rays as a branch of optics Nobel Lecture, December 12, 1927

Evidence for the existence of electrons of this type producing "very short tracks." was appearing in the Wilson Cloud Chamber. Here is very brief article from Letters where A. H Compton and C. T. R. Wilson chime in support of each others work on that topic:

Recoil of Electrons from Scattered X-Rays: A. H. Compton & C.T.R. Wilson Letters to Editor, Nature SEPTEMBER 22, 1923

by **Solar** » Tue Dec 08, 2020 7:27 pm

Next document(s) for your reading pleasure:

Article: Scientist unveil new discoveries about gamma ray flashes coming from thunderstorms 10 December 2019 (links to papers at bottom)

Observed sequence detected by ASIM per the article:
1- “The optical (visible light) pulse comes after the TGF”
2- “TGFs are created immediately in front of and before a pulse of electricity shoots through the leader of charged air that becomes a lightning bolt,”

PAPER: Open Access

The Atmosphere‐Space Interactions Monitor (ASIM) was launched to the International Space Station on 2 April 2018. The ASIM payload consists of two main instruments, the Modular X‐ray and Gamma‐ray Sensor (MXGS) for imaging and spectral analysis of Terrestrial Gamma‐ray Flashes (TGFs) and the Modular Multi‐spectral Imaging Array for detection, imaging, and spectral analysis of Transient Luminous Events and lightning. ASIM is the first space mission designed for simultaneous observations of Transient Luminous Events, TGFs, and optical lightning. During the first 10 months of operation (2 June 2018 to 1 April 2019) the MXGS has observed 217 TGFs. In this paper we report several unprecedented measurements and new scientific results obtained by ASIM during this period: (1) simultaneous TGF observations by Fermi Gamma‐ray Burst Monitor and ASIM MXGS revealing the very good detection capability of ASIM MXGS and showing substructures in the TGF, (2) TGFs and Elves produced during the same lightning flash and even simultaneously have been observed, (3) first imaging of TGFs giving a unique source location, (4) strong statistical support for TGFs being produced during the upward propagation of a leader just before a large current pulse heats up the channel and emits a strong optical pulse, and (5) the t50 duration of TGFs observed from space is shorter than previously reported First 10 Months of TGF Observations by ASIM - N. Østgaard T. Neubert V. Reglero K. Ullaland et al

The only 'definite' sequence that that has been consistently detected is that TGF's occur before the emission of optical light.

Section 3.2.1 Simultaneous TGF Observation From Two Platforms: along with Figure 3 shows interesting detection capabilities between ASIM, Fermi, and WLLN

Section 3.2.3 TGF and Elve Produced by the Same Lightning Flash: Along with Figure 5 (particularly panel C) shows at t=0 that TGF is "simultaneous" with current pulse. Time is in microseconds. Notice that "weak rise" occurring between -500 - 0 us. This "weak rise" ~0.5-1 ms before the TGF has been observed in all observations and seems to suggest the onset of ionization of Nitrogen and Oxygen. The TGF occurs 10 us before the Elve which occurs further up in the ionosphere at UV 180-240 nm.

Section 3.2.4. The Sequence of TGF and Main Optical Lightning Pulse: things can get slightly confusing here because the authors begin to offer a few interpretations where the "weak rise" precedes the TGF; the TGF then occurs simultaneous with the current pulse, but then this "weak rise" is interpreted as being due to an increase in two 'lightning leader channels' about 1-2 ms before the TGF. This is a case where "the TGF is produced during the leader propagation about 500 us before the onset of a current pulse.".

Further interpretation of the detections are narrowing the occurrence of TGF's occurring 0-320 us "before or at the onset of the current pulse." In 3.2.4. I think it good suggestion that some of the events are the result of leader development and propagation. Its easy to see that things are not nailed down and further assistance from WLLN is going to be necessary. There is a +/-80 us timing uncertainty between the MMIA and MXGS modules. With some detections occurring within so little as 10 us you can see why its going to take a coordinated effort to try and tease the data that might show which comes first between TGF and current pulse. The bottom right corner of every page is a page number. On page number 14,034 the last sentence above Figure 8 states where the team's work was at as of this paper. The detections see:

"Weak rise" ----> TGF's occurring 0-320 us before ----> within 10 us Elve ----> large current pulse ----> then optical pulse. Somewhere in the midst of that sequence a lightning "Leader" is suggested to develop and begin to propagate.

Just sharing a few notes.

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