Rules Only: PA as Ortillery

[McPerth]

In CT/MT and I guess other rules sets, starships PA weapons were not usable as ortillery against atmosphere protected planets. I don't find anything about such restriction in MgT.

Are they then usable against ground targets in planets with atmosphere in MgT?

 

[SpaceBadger]

I think the problem is the two kinds of particle accelerators. I am talking real life; I don't know if this distinction is made in MgT or not.

Charged Particle Accelerators work in atmosphere, but not so well in space as the particles repel each other and there is nothing to keep them together.

Neutral Particle Accelerators work in space, but not so well in atmosphere - umm, sorry, I don't recall why that is, perhaps one of our local physics gurus can explain.

What it boils down to is that you probably have NPA as a ship-to-ship weapon, and that is not going to do well as ortillery firing down into an atmosphere. If your ship carries a CPA for use in atmosphere, you are going to have to go down into atmosphere to use it, not fire it from orbit, as the particles will scatter too much to be a useful beam weapon.

 

[Lycanorukke]

Charged Particle Accelerators work in atmosphere, but not so well in space as the particles repel each other and there is nothing to keep them together.

Neutral Particle Accelerators work in space, but not so well in atmosphere - umm, sorry, I don't recall why that is, perhaps one of our local physics gurus can explain.

Very roughly, the C-PAW 'self pinches'. As the beam hits atmosphere, it starts ionizing the air, the ionized air generates a current which in turn confines the C-beam allowing it to avoid dispersion for a time. It essentially makes a tunnel for itself.

The N-PAW not being charged doesn't 'self pinch' due to ionization to as great an extent (there is some of course) and hence disperses fairly quickly in the atmosphere.

A PDF paper from 2009 on it here (chapter 5 deals with atmos pinching)The Physics of high-intensity, high-energy Particle Beam Propagation in open Air and outer-space Plasmas

 

[McPerth]

This was also explained in the article Spinal Weapons Revised, by Keith Douglas (JTAS 20, pages 40-45), where it explains (among other things) why starships PAs must be N-PAWS (Neutral Particle Acceleration Weapons Systems), and so ineffective in atmosphere. I guess that was the basis for them not to be usable as oritillery in planets with atmopshere.

But in MgT traveller, none of this is commented, so, with the letter of the rules as they are writen, nothing precludes you to use them as such.

 

[whulorigan]

Very roughly, the C-PAW 'self pinches'. As the beam hits atmosphere, it starts ionizing the air, the ionized air generates a current which in turn confines the C-beam allowing it to avoid dispersion for a time. It essentially makes a tunnel for itself.

The N-PAW not being charged doesn't 'self pinch' due to ionization to as great an extent (there is some of course) and hence disperses fairly quickly in the atmosphere.

Which also raises the issue:

Why are there no battlefield C-PAWS in any of the Traveller Rulesets other than Battlefield Meson Guns (at least, AFAIK, I don't believe any have ever been detailed)?

Has anyone ever designed any that were published?

 

[Lycanorukke]

Why are there no battlefield C-PAWS in any of the Traveller Rulesets other than Battlefield Meson Guns (at least, AFAIK, I don't believe any have ever been detailed)?

At a guess it would be because PA's are line of sight weapons, which defeats a major point of artillery (indirect fire). Ortillery gets around this by being overhead in orbit, but for ground weapons - you may as well use a big fusion gun to shoot things instead of a fiddly, bulky and expensive PA system. Meson guns of course dont have this problem as they could be on the other side of the planet and still hit a target.

(Apologies to McPerth for sidetracking from the 'Rules only' header )

 

[McPerth]

(Apologies to McPerth for sidetracking from the 'Rules only' header )

No need to apoligize. Rules only doesn't (IMHO) preclude talking about the reasoning that is (or should be) under those same rules.