Page 1 of 3

Particle Beams, Pulse Lasers and Beam Lasers

Posted: Tue Jun 01, 2010 3:23 pm
by Egil Skallagrimsson
OK, I might well have missed something here. When I first read the rules, I assumed that particle beams, as a radiation based weapon, could be defended against by using nuclear dampers. Then, on a re-read, I realised that this didn't seem to be so, they seemed to be more of a beam weapon. Surely, then, sandcasters could be used to break up the beams. Well, that doesn't seem to be the case either, only armour seems to help (until TL16+ anyway). Have I missed something?

About a week before the HG errata was published, I came to the same conclusion that the only way to limit the particle beam super weapon was to reduce to one per turret, but for the sake of book keeping, require a triple turret to be fitted (to accomadate all the extra cooling required). Still cannot see why particle beams should not be vulnerable to sand or nuclear dampers. Have I missed something? Currently, provisionally, MTU allows nuclear dampers to reduce the effect of particle beam by -2d6 on a successful screen roll, though not had to use the rule (as player free trader lacks particle beams and screens, and not likely to gain such expensive military grade technology anytime soon!).

On a different tack, I don't understand why the pulse laser and beam laser stats from the core rule book were modified in HG. Tried using the HG changes for a while, and have now (MTU) gone back to the core rulebook. What was the thinking behind the change?

Any thoughts?

Egil

Posted: Tue Jun 01, 2010 5:05 pm
by Rikki Tikki Traveller
Particle beams in Traveller use neutrons, so there is no decay, so a Nuclear Damper would have no effect.

Large sand particles (large on an atomic scale) will also not have an appreciable affect on a stream of neutrons, so Sand doesn't affect them much either. If you had something with a density approaching air, then you would get an affect, but not from a few charged, prismatic particles floating in space.

Posted: Tue Jun 01, 2010 5:26 pm
by Egil Skallagrimsson
Thanks, that makes (to a non-physicist!) sense, particle beams clearly are a wonder weapon, astonishing that something from TL8 has got no counter measure until TL16. Time to scrub that house rule.

Thinking about nuclear weapons (not a happy thought), nuclear missiles and, especially, nuclear tipped torpedos seem ridiculously weak. Hard to see how such a weapon, especially against an unarmoured target, wouldn't simply tear a large hole and cripple something like a Far trader, not just inflict, on average, 2 single hits (missile), or three single hits (torpedo).

Egil

Posted: Tue Jun 01, 2010 5:29 pm
by Rikki Tikki Traveller
Agreed. Maybe they are tactical nukes in the kiloton range, so they have much lower yields than you are used to seeing from modern/historical examples.

Posted: Tue Jun 01, 2010 5:45 pm
by Egil Skallagrimsson
I was assuming tactical nukes in the sub 1kt yield, something akin to nuclear artillery shells or nuclear torpedos or depth charges, still would have thought they would do more damage than double the equivelent weight of high explosive.

I feel another MTU rule coming on.

Egil

Posted: Wed Jun 02, 2010 4:22 am
by BP
FYI: A nuclear weapon exploded in the near vacuum of space has a radically different complexion of weapon effects than one detonated in atmo:

1) In the absence of an atmosphere, blast disappears completely.
Basically, it becomes a kinetic impact weapon (though with slightly increased yield assuming contact with material - but without significant blast overpressure associated with atmo detonated weapons).

2) Thermal radiation, as usually defined, also disappears.
There is no longer any air for the blast wave to heat and much higher frequency radiation is emitted from the weapon itself.

3) In the absence of atmo, nuclear radiation will suffer no physical attenuation and the only degradation in intensity will arise from reduction with distance (square of the distance).
Thus, the range of significant dosages will be many times greater than at ground level in atmo.

So basically, its not much different than a conventional weapon in terms of relative yield - except it produces high doses of radiation which quickly taper off with distance...

(Though, don't forget EMP - since that is important if your equipment is not shielded - and for larger yield weapons, can have a significant impact on a global scale and in near-planet orbits...)

Posted: Wed Jun 02, 2010 4:39 am
by apoc527
This is mostly correct, but information from Atomic Rocket indicates that nukes are still quite effective weapons because of the sheer energy of the x-ray burst that would otherwise be absorbed by the atmosphere (and which is the cause of the thermal and blast wave effects in atmosphere).
Nuclear weapons will destroy a ship if they detonate exceedingly close to it. But if it is further away than about a kilometer, it won't do much more than singe the paint job and blind a few sensors. And in space a kilometer is pretty close range.

Please understand: I am NOT saying that nuclear warheads are ineffective. I am saying that the amount of damage they inflict falls off very rapidly with increasing range. At least much more rapidly than with the same sized warhead detonated in an atmosphere.

But if the nuke goes off one meter from your ship, your ship will probably be vaporized. Atmosphere or no.
He goes on in some detail here:


http://projectrho.com/rocket/rocket3x1.html#nuke[/url]

Posted: Wed Jun 02, 2010 11:08 am
by Egil Skallagrimsson
Very impressed with the Atomic Rocket site, thanks apoc527, though still working through some of the maths. The site is rather doubtful about particle beams, and also raises some interesting points about the difficulty of hitting a small, fast moving, probably dodging, target at ranges in excess of 10,000km. Even assuming the super computers of the future, this seems a very big ask. Missiles, able to correct in flight, have some advantages.

I was assuming a direct hit with a nuclear warhead, so the limited area effect in space not so important.

So, drawing heavily on the Atomic Rocket site for ideas, and on a strictly MTU basis;
1. Pulse and beam lasers as core rulebook.
2. Particle beams limited to short range. Any particle beam turret can be switched to passive, defensive role creating a field of charged ions that will repel other particle beam attacks, creating a shield of 2d6+effect
3. Conventional missiles and torpedos as core.
4. Nuclear missile 6d6 dam, nuclear torp 18d6 dam, both + emp and rad (yes, it is supposed to be a ship killer), nuclear warheads tightly controlled by governments!
5. Meson weapons, not decided what to do about these yet.
6. Point defence by lasers, and by kinetic weapons similar to phalanx, but perhaps using gauss technology as well.
7. Missiles can also used to intercept incoming missiles.

Any thoughts?

Egil

Posted: Wed Jun 02, 2010 12:46 pm
by locarno24
Even assuming the super computers of the future, this seems a very big ask. Missiles, able to correct in flight, have some advantages.
That's why it the Honor Harrington and early Andromeda (less the many powers of ten for accelerations), or Reality Dysfunction series combat often seems more believable....
Particle beams in Traveller use neutrons, so there is no decay, so a Nuclear Damper would have no effect.
....Wait, how do you accelerate a neutron? Alpha or Beta particles are both electrically charged, so a big coil can fling them quite efficiently, but neutrons? I missed that bit.
Nuclear missile 6d6 dam, nuclear torp 18d6 dam, both + emp and rad (yes, it is supposed to be a ship killer), nuclear warheads tightly controlled by governments!
Fair enough.....to be honest, the main thing never really covered is EMP, which is the biggest advantage to a nuclear tip. Obviously a contact nuke detonation is a pretty terminal experience.

Again, using HH and RD series, you tend to find that the nuke is usually a bomb-pumped laser warhead, which makes more sense from a damage perspective.
Point defence by lasers, and by kinetic weapons similar to phalanx, but perhaps using gauss technology as well.
PD lasers are fine - kinetics depends on the type of missile and its speed - a bomb-pumped weapon, as above, is going to go off at a range that intercepting it with ballistic defences is going to be very difficult.
Missiles can also used to intercept incoming missiles.
Again, depends on the capability of the missile - a 'blunt' nuke is probably best, using its EMP to fry the attacking missile's terminal sensors.

Other than that you're essentially looking for a direct hit (given the size of any potential frag cloud) against a small target moving at many kilometres per second. See the incompetent flailings of the various US ballistic missile defence programmes for a good summary on how hard this is.
Yes, computer and engine power increases, but that also means the attacking missile is closing faster, evading better and is hidden inside a thicker cloud of ECM that you have to burn through, so it probably doesn't get discernably easier with TL*. Anti-missile-missiles is fine, but they would definitely have to be a dedicated countermissile design to be effective, and certainly to be cost-effective.

At fairly high TL, I can imagine 'missiles' being essentially have a high-G, AI controlled baby spaceship with a clutch of multi-function submunitions, very much like the Reality Dysfunction 'Combat Wasp'.

Posted: Wed Jun 02, 2010 12:48 pm
by BP
apoc527 wrote:This is mostly correct, but information from Atomic Rocket indicates that nukes are still quite effective weapons because of the sheer energy of the x-ray burst that would otherwise be absorbed by the atmosphere (and which is the cause of the thermal and blast wave effects in atmosphere).
:D Sorry - X-Rays are a form of electromagnetic radiation!

The relevant line from the site you mis-interpreted, is: There ain't no atmosphere in space so the nuclear explosion there is light on blast and heavy on x-rays.

Further, the blatant statement 'But if the nuke goes off one meter from your ship, your ship will probably be vaporized. Atmosphere or no. ' is not only completely unsubstantiated - it neither provides for the fact that there are different scales of weapons (such as a tactical field nuke vs. a planet-buster cobalt salted device...) nor that the nature of the material of the ship. So, that statement can always be refuted when qualified (bear in mind this is an very nice site run by a computer guy/game designer and player for a good number of years!) - and he doesn't specifically state that he is mostly talking about megaton yield plus nukes.

Delicate things like electronics (and sophont cells) are going to be the most affected. Things like titanium hulls may, in the extreme, become embrittled - but mostly will just become radioactive themselves. A meter away is an incredibly huge distance for 'vaporization' (basically becoming part of the chain reaction).

Posted: Wed Jun 02, 2010 1:10 pm
by Rikki Tikki Traveller
locarno24 wrote:....Wait, how do you accelerate a neutron? Alpha or Beta particles are both electrically charged, so a big coil can fling them quite efficiently, but neutrons? I missed that bit.
Well, initially you can't. Early PAWs use charged particles, electrons and protons. Protons pack more punch and have better atmospheric penetration.

At TL-9+, you can use gravitics to accelerate Neutrons which have even better penetrating power in atmosphere and not affected by electro-magnetic fields.

When a Neutron hits another atom it causes radiation damage (and secondary radiation effects) in addition to any damage from the accumulated kinetic energy of the stream.

Posted: Wed Jun 02, 2010 2:06 pm
by locarno24
Aha.....the default traveller answer - It's All Done With Gravetics (TM)

Kind of feels like there should be a differentiation between the two - as noted above, counter-fire with an equivalently charged beam would affect an early weapon (the crossfire region between two ships with proton-firing alpha-particle beams would get a bit wierd, with the beams refracting one another somewhat if they cross one another....)

Posted: Wed Jun 02, 2010 2:54 pm
by Egil Skallagrimsson
I suppose I am envisaging space combat as somewhat similar to The Reality Function's combat wasps at higher tech levels, say above11, and similar to modern wet naval warfare below. The use of particle beams to deflect other beams looks feasable (probably a good deal more feasable than sand casters).

Developing missiles to intercept attacking missiles would just be developing existing practice, more challenging but certainly not beyond the realms of the possible.

The more I think about it, the more convincing a torpedo with a nuclear contact warhead looks as a ship killer. The release of that much energy directly onto a space ship must be devestating, only a very heavily armoured or large vessel will be ok.

Egil

Posted: Thu Jun 03, 2010 1:06 pm
by Rikki Tikki Traveller
So your vision is something like the new BSG?

Missiles and rail guns firing all over the place and the occasional nuclear torpedo that can destroy the big boys, or at least severely damage them?

Posted: Thu Jun 03, 2010 1:53 pm
by apoc527
The Galactica took a nuke and sustained relatively small amounts of damage. Granted, it's designed to take those hits and any lesser ship would be screwed.

Posted: Thu Jun 03, 2010 4:02 pm
by BP
apoc527 wrote:... and any lesser ship would be screwed.
All things are relative - and again, in space, the major difference between nuclear vs. conventional weapons is the radiation - not the 'blast'.

Posted: Fri Jun 04, 2010 1:05 am
by phavoc
BP wrote:FYI: A nuclear weapon exploded in the near vacuum of space has a radically different complexion of weapon effects than one detonated in atmo:

1) In the absence of an atmosphere, blast disappears completely.
Basically, it becomes a kinetic impact weapon (though with slightly increased yield assuming contact with material - but without significant blast overpressure associated with atmo detonated weapons).

2) Thermal radiation, as usually defined, also disappears.
There is no longer any air for the blast wave to heat and much higher frequency radiation is emitted from the weapon itself.

3) In the absence of atmo, nuclear radiation will suffer no physical attenuation and the only degradation in intensity will arise from reduction with distance (square of the distance).
Thus, the range of significant dosages will be many times greater than at ground level in atmo.

So basically, its not much different than a conventional weapon in terms of relative yield - except it produces high doses of radiation which quickly taper off with distance...

(Though, don't forget EMP - since that is important if your equipment is not shielded - and for larger yield weapons, can have a significant impact on a global scale and in near-planet orbits...)
Wouldn't the impact from thermal radiation be relative the distance from the detontation? It's still going to generate a great deal of heat, but in the vacum of space it will dissipate quite quickly. Though I would suppose objects would be more heavily impacted by the x-rays instead of the thermal yield.

Which gives an interesting conundrum... say if you had collapsed matter as your hull armor... most x-rays wouldn't be able to penetrate that sort of density would they? After all, a relatively light level of lead protects against light radiation, though not gamma rays, which require much more massive shielding.

And as another aside (darn brain!), doesn't water also function as a barrier against radiation?

Posted: Fri Jun 04, 2010 2:32 am
by BP
Your interest is great - really wish I had the communication and teaching talent to address all that!

Unfortunately, you are speculating on a complicated subject that is also not easily related to everyday experiences... hopefully someone here can 'explain' things in a way you can relate to. (I'd just confuse you more :( )

Posted: Fri Jun 04, 2010 7:51 am
by locarno24
All things are relative - and again, in space, the major difference between nuclear vs. conventional weapons is the radiation - not the 'blast'.
Depends. Whilst you can't tell for definite, it looked like a contact detonation - which means a direct transfer of the energy from warhead to target and full-blown briscance from physical and thermal shockwaves.

The fact that it not only survived but lost virtually no fighting ability means Galactica is actually, therefore, built like a brick outbuilding inside another brick outbuilding protected in a bunker under a large mountain.....

Wouldn't the impact from thermal radiation be relative the distance from the detontation? It's still going to generate a great deal of heat, but in the vacum of space it will dissipate quite quickly. Though I would suppose objects would be more heavily impacted by the x-rays instead of the thermal yield.
Yes. If a nuke is a point source expelling any sort of radiation in (roughly) a thin (since it's a 'moment of blast' thing) uniform sphere, then the amount you catch is proportional to the percentage of the surface area of that sphere you cover at the moment the 'shell' of radiation hits you.

The radiation strength per unit area is divided by the radius from the bomb, squared. So it drops quickly from a near miss - double the distance, quarter the effect.
Which gives an interesting conundrum... say if you had collapsed matter as your hull armor... most x-rays wouldn't be able to penetrate that sort of density would they? After all, a relatively light level of lead protects against light radiation, though not gamma rays, which require much more massive shielding.
Collapsed matter (depending on the level of collapse*) verges on being solid material on an atomic level. Which means that a packet of radiation can't pass through without striking a particle, and even if it's re-emitted (depending on the radiation) it does so in a random direction, which means only a one-in-six chance of it carrying on in roughly the same direction as previously (think of a d6's faces). Plus it's likely to be absorbed and re-emitted multiple times, scattering all the radiation randomly. Particle radiation is even less likely to penetrate - since if it strikes another nucleus, it'll generally be absorbed and collapsed matter isn't going to shed particles to compensate.

It should be bourne in mind, though, that, 'extreme physics' like neutronium aside, radiation shielding blocks a percentage of the radiation coming through - that percentage depending on the type of shielding, the type of radiation, and the thickness of the shielding. The proportion will never be 100%, no matter how much effort you put in. This is why you have detectors in huge tanks of water buried half a mile underground (about the only bit of science 2012 got right) that can still watch cosmic radiation.
And as another aside (darn brain!), doesn't water also function as a barrier against radiation?
Yes. But, again, it's only reducing the radiation by a percentage. Otherwise your body (which is 70% water) would be completely opaque to x-rays.







* Non-pauli material with imploded electron shells or full-blown neutronium

Posted: Fri Jun 04, 2010 10:50 am
by Egil Skallagrimsson
So your vision is something like the new BSG?
Partly, though I am not sold on the WWII battle of Midway approach, works brilliantly in the series, but, without the universes best, and most miniturised, FTL allowing small craft to jump in and jump away after firing, I see space fighters as death traps.

No, still thinking about space combat based on missile exchanges, simiilar to Hamilton's combat wasps. Primarily, the idea is to overwhealm your opponents distant defences (based on intercepter missiles) and point defence (lasers and rail guns) while trying to avoid distraction from ECM.

Galatica is, clearly, super tough, and also large enough to sustain severe damage in one section and still fight. That would still be possible if damage from nuclear warheads, especially on torpedos, was increased substantially. However, 1000 ton unarmoured craft had best keep out of the way.

Egil