Fusion vs Plasma vs Lasers

[Supertank]

So I think I'll use my first post to tackel one of my most nagging question, one which doesn't seem to have come up so far:

1) What makes a Fusion Gun more desirable than a Plasma Gun?

Sure, the fluff mentions how Fusion Guns are more damaging because they can reach greater temperatures, but as far as I can tell the only functional difference between the weapons is that Plasma Guns are cheaper and not affected by Nuclear Dampers.

2) What makes either of these guns more desirable than Lasers?

In most editions the trusty Beam Laser and Pulse Laser are turret-only weapons. But in T5 they can be used with any mount, so they're now also competing with Fusion and Plasma Guns for Barbette real estate.

Now Laser Barbettes seem to have many perks over Fusion/Plasma: They're cheaper, they have inherent effects (Beam being more accurate, Pulse being more damaging), and there are fewer defenses that can stop Lasers (whereas Fusion/Plasma can be stopped by everything that can stop Lasers, plus a few additional systems).

I think maybe I have skipped something regarding a weapon's base TL having some effect that you can't get by just upping the TL of an earlier weapon systen, but that doesn't appear to be the case.

(I'm personally gravitating towards making Fusion/Plasma hits partially penetrating, or just add Hits to keep it simpler.)

 

[agorski]

Welcome aboard!

I haven't checked, but in CT lasers had longer range.

 

[whulorigan]

So I think I'll use my first post to tackel one of my most nagging question, one which doesn't seem to have come up so far:

1) What makes a Fusion Gun more desirable than a Plasma Gun?

Sure, the fluff mentions how Fusion Guns are more damaging because they can reach greater temperatures, but as far as I can tell the only functional difference between the weapons is that Plasma Guns are cheaper and not affected by Nuclear Dampers.

2) What makes either of these guns more desirable than Lasers?

In most editions the trusty Beam Laser and Pulse Laser are turret-only weapons. But in T5 they can be used with any mount, so they're now also competing with Fusion and Plasma Guns for Barbette real estate.

Now Laser Barbettes seem to have many perks over Fusion/Plasma: They're cheaper, they have inherent effects (Beam being more accurate, Pulse being more damaging), and there are fewer defenses that can stop Lasers (whereas Fusion/Plasma can be stopped by everything that can stop Lasers, plus a few additional systems).

I think maybe I have skipped something regarding a weapon's base TL having some effect that you can't get by just upping the TL of an earlier weapon systen, but that doesn't appear to be the case.

(I'm personally gravitating towards making Fusion/Plasma hits partially penetrating, or just add Hits to keep it simpler.)

Shortly before the publication of T5.10, I sent these errata suggestions directly to Marc Miller. Unfortunately, I do not think they were received until after the books went to print. Here are my obersavations and Marc's responses:

My Observations/Suggestions:

Book 2, How Weapons Work, p.158 (Typical Weapons): Clarification/Suggestion - Single Pulse Lasers are said to do 2D as compared to Single Beam Lasers doing 1D. In light of this:

a) Does this mean an additional 1D per barrel, or an additional 1D total for the turret (i.e. does a triple pulse laser do 4D or 6D)?

b) In light of "a)" above, the Plasma & Fusion Gun mentioned on this page should be similarly differentiated - A TL12 Standard Fusion Barbette and a Standard Plasma Barbette built at TL12 will both do the same damage and otherwise be identical, save that the Fusion Gun will cost half-again as much: I suggest adding an additional 1D damage to the Fusion Gun as compared to the Plasma Gun to make a distinction between the two weapon systems.
​

Marc Miller's Response:
The text is unclear or deficient. I believe Pulse Laser is +1D for the Mount. Your suggestion for Fusion is a good one.

 

[Spinward Scout]

1) What makes a Fusion Gun more desirable than a Plasma Gun?

The atoms are heavier once fused - it's no longer hydrogen, it's now helium. It should cause more damage. Other than that, the heat (relative to a human and many materials) should be pretty comparable.

 

[whartung]

The atoms are heavier once fused - it's no longer hydrogen, it's now helium.

Um...yea, I guess. You get atoms that are twice as heavy, but you have half as many of them.

 

[whulorigan]

I think Supertank's question has to do with what makes a Fusion Gun more desirable than a Plasma Gun in game terms from a game mechanics standpoint. Otherwise, why would anyone even build/buy a fusion gun if a plasma gun is otherwise identical in terms of its effects.

 

[Condottiere]

I kinda doubt that in terms of spaceship design it's ever made clear except in terms of damage potential, technological level, energy expenditure, and cost.

On the more personal level, you need a battle dress to compensate for the recoil, the weight of the weapon system itself, and probably against radiation exposure.

You can scale laser weapon systems, but reflec and ablat are specifically designed to counter it.

Lasers can also be used defensively, and probably it's easier to obtain parts for repairs and maintenance.

 

[Supertank]

Shortly before the publication of T5.10, I sent these errata suggestions directly to Marc Miller. Unfortunately, I do not think they were received until after the books went to print. Here are my obersavations and Marc's responses:

Ah, that makes a bit more sense. Probably add an extra +1D for both Plasma and Fusion to differentiate them from the Lasers.

On the more personal level, you need a battle dress to compensate for the recoil, the weight of the weapon system itself, and probably against radiation exposure.

They are distinct enough with the GunMaker, but on the ship scale they are effectively identical.

You can scale laser weapon systems, but reflec and ablat are specifically designed to counter it.

Lasers can also be used defensively, and probably it's easier to obtain parts for repairs and maintenance.

Not quite. Plasma and Fusion Guns can also be used defensively, and every ship defense that works on Lasers also works on Plasma and Fusion Guns.

 

[AnotherDilbert]

Not quite. Plasma and Fusion Guns can also be used defensively, and every ship defense that works on Lasers also works on Plasma and Fusion Guns.

Yes, Plasma and Fusion Guns is strictly worse than Lasers, and completely useless in T5.

All of them are very short ranged, and so low powered that they can't hope to penetrate the armour of even a Free Trader.

Basically, they are not offensive weapons, but point defence batteries. So why bother making them slightly better as weapons?


If you actually want to hurt the enemy you use missiles or particle accelerators.

 

[Spinward Scout]

Um...yea, I guess. You get atoms that are twice as heavy, but you have half as many of them.

Unless there's a pre-firing Fusing chamber.

If the hydrogen is fused in the same chamber that the 'Fusion Bolt' is released from, then you're right - there's no extra space to add more fused Helium.

But I think I kinda went off-topic, sorry.

 

[Supertank]

I wonder if there's something to reverse-engineer from the Nuclear Damper description:

Fusion gun output does not produce fusion reactions (the weapon is reduced to a poor level of plasma gun performance; hits inflicted are halved).

Reduced to (a poor level of) Plasma Gun performance = half hits.

So could this mean Fusion Guns deal double the hits by default, letting them tear into ships that don't have Nuclear Dampers?

All of them are very short ranged, and so low powered that they can't hope to penetrate the armour of even a Free Trader.

T5 ship armor is ablative. Enough laser beams will get through.

 

[Magnus von Thornwood]

Not Bolts, Beams!

Unless there's a pre-firing Fusing chamber.

If the hydrogen is fused in the same chamber that the 'Fusion Bolt' is released from, then you're right - there's no extra space to add more fused Helium.

But I think I kinda went off-topic, sorry.

Turns out in T5 plasma and fusion weapons do not fire bolts but beams.

/snip/
T5 ship armor is ablative. Enough laser beams will get through.

There is ablative Layer (for Heat if I recall) but normal starship armor is either yes or no when it comes to penetration. You need to hit and do damage over the Armor value for a hit to penetrate into a compartment. So, enough laser beams with enough power can punch through armor but if they don't have the dice to beat the AV they're just sparkly lights that mess up the paint and leave scoring.

 

[Supertank]

There is ablative Layer (for Heat if I recall) but normal starship armor is either yes or no when it comes to penetration. You need to hit and do damage over the Armor value for a hit to penetrate into a compartment. So, enough laser beams with enough power can punch through armor but if they don't have the dice to beat the AV they're just sparkly lights that mess up the paint and leave scoring.

Book 2, p. 195. Hits reduce the Armor Value of the outermost layer. This is where Polymer armor comes in handy, as it effectively restores the AV of any still functional layer each turn.

Heat, being a protection afaik, should be more of an all-or-nothing affair.

You can scale laser weapon systems, but reflec and ablat are specifically designed to counter it.

They also counter Fusion/Plasma, so it's not too bad of a deal.

 

[robject]

THE POINT

The point is clear: plasma and fusion weapons are niche weapons, to say the least, and in an ACS context they're basically just real expensive emplacement-restricted mining lasers.

"Don't Bother With Them!"

^^^^ I do know that that's exactly the intended reaction.

Laser weapons are ubiquitous, and plasma-based weapons are rare... well by ACS rules it's quite clear that that will be the case... overwhelmingly so. I mean there's NO discussion over that! Crystal clear! Holy war averted!

ACS always prefer lasers. Perhaps *that* is the goal.

"Then why have plasma/fusion guns there in the first place?"

Because they do exist and can crop up. They just don't make sense in an ACS context.

"Yeah so then in what context?"

^^^ I think that is the correct question.


THE PROBLEM

The various lasers and the two plasma-based weapons, in Traveller5, have bothered me for as long as I can remember. I think there are bits that ACS cannot sort out.

* In their definition, fusion guns have greater effect and damage than plasma... but you won't find the mechanics that lay this out.

* In their definition, fusion and plasma guns inflict heat and kinetic damage... but you won't find this in the specific mechanics.

Yet this defines the niche for plasma and fusion guns. But ACS lacks the supporting mechanics.



THE POSSIBILITY

I think Plasma and Fusion guns provide a niche benefit in a BCS context that's just not there in an ACS context. I really don't know what that would be -- perhaps power or resource management on a grand scale. Or perhaps point defense on Capital Ships and fighter clouds.

Since in Classic Traveller these energy weapons don't show up until we get High Guard, that might be the theoretical key.

 

[robject]

Okay, I'm speaking with Marc Miller now, and he has a slightly different angle for it, which isn't in the rules.

ACS Context

Naturally Marc pointed out that Plasma and Fusion guns do have an ACS context: for example, a Gazelle might want one. But he also commented that a 600t cargoliner could justify/absorb the space and cost of a plasma barbette, so there's also a civilian context.

But, he concedes that a Beowulf shouldn't really care for one. In other words, whatever the benefit, it's not worth MCr1 and losing a couple tons of space.

And so we talked about what lasers and plasma guns are, and how they are different. Particle size, interaction with environments, and focus. Lasers have great focus, but an atmosphere could potentially dissipate them. Plasma presumably could as well, but if they're gravitically focused, does that say anything about their performance in an atmosphere?

In Atmospheres?

ASSUME THEN that the gravitically-focused plasma-based guns work fine in atmospheres... whereas lasers may suffer in the same way particle accelerators suffer. Thus, "high guard" escorts might want plasma guns, and military vessels might want to (often) mount plasma weapons, due to their disregard for atmosphere, over lasers, which work fine in a vacuum but suffer range or damage effects (which??) in atmospheres (and by how much, and how does air density affect that?).

There are unanswered questions, but that was the direction of thought.

 

[Condottiere]

Fusion is meant to punch through armour at close range.

Laser is meant to be more flexible, though less powerful.

Whether this actually balances out in gameplay ...

 

[AnotherDilbert]

Book 2, p. 195. Hits reduce the Armor Value of the outermost layer. This is where Polymer armor comes in handy, as it effectively restores the AV of any still functional layer each turn.

Certainly, but a laser turret does 3D (≈10) damage and a TL12 Free Trader with a free coating and a free armour anti-layer has armour 2400 vs Heat/Beam.

It would take about 240 hits at the same damage location to penetrate the armour. The target ship has presumably become bored and left local space before that happens...

 

[Panzerkraken]

I don't see any indication in the actual starship rules that they use the personal-scale damage types; which is to say that the damage from a Laser or Plasma/Fusion gun would just be damage, applied against AV instead of against the Heat Protection (which only really comes into play when using the meteoric ascent/descent rules). All the examples in the weapon section specifically place the damage of beam weapons against AV.

The atmospheric considerations could be a thing, and the mechanics to make it work wouldn't be hard (say that lasers have a -mod to damage per range band depending on the atmosphere rating of the planet, something like Atm# -5 would work well..) to implement.

 

[AnotherDilbert]

I don't see any indication in the actual starship rules that they use the personal-scale damage types; which is to say that the damage from a Laser or Plasma/Fusion gun would just be damage, applied against AV instead of against the Heat Protection (which only really comes into play when using the meteoric ascent/descent rules).

Take a look at B2 p202. Ablat and Reflec coatings specifically work against Lasers (+ Plasma and Fusion).


Armour is ablative, any attack removes a bit of armour and the next attack will have less armour to penetrate.

Protection is not ablative, it either works or is penetrated. The next attack will find the same protection regardless of whether the last attack penetrated or not.

Penetration. For each Hit, Attacker notes the Target Compartment and applies Flux to determine actual Hit Compartment (if empty, the Attack ends).
Attacker applies the Weapon Hits in D against the Hit Compartment’s Armor and Protection.
Against Armor, Hits reduce the AV Armor Value and, if AV is reduced to zero, they Penetrate.
Against Protections, Hits are compared to AV Armor Value and (if AV is exceeded, they Penetrate).
Failure to Penetrate stops the Attack.

Protection is e.g. Rad and EMP values.

Non-Destructive Effects. Some effects (EMP, Rad) are non-destructive; the effect penetrates without destroying.

For armor "Heat x100" simply means AV×100 vs Heat (e.g. Lasers).

Anti-Layers provide additional protection against specific threats. Anti-Layers are specialized versions of the ship’s Armor. A TL-12 ship with Structure= Polymer has Armor Layers built with Polymer. It has a base AV= TL/2= 6. One or more Layers can be designated Anti-Blast, which confers a multiplier x10 (AV= 60) against Blast, Bullet or Frag. Its AV against other attacks remains the same.

So, the noted AV for the structure and TL is the Base AV. Effective AV against specific attacks may be larger.

Note that p202 says which anti-layers works against which weapons; all of them works against Lasers.

I agree it is not very clear...

T5.09 was clearer:

Various Armor Values are increased against specific Attacks. After the various calculations, round the result down to the nearest whole number. AV-11 is x100 against Heat (which includes Beams, Lasers). A Laser attack inflicting 5D= 30 Hits reduces AV-11 from 1100 to 1070; round down.
Armor Values reduced by a Hit are reduced permanently until repaired.

 

[whartung]

But ACS lacks the supporting mechanics.

To be blunt, it's a game. If there's no supporting mechanics, then there's "no point". You're talking color of the light saber now.

"We use purple lasers, as my daughter liked the color."

"Why do you have a bright floral print on your BDUs?" "It's Spring!"