Scifi Space Plasma Cannons... Totally Useless?

[KSK]

6 hours ago, kerbiloid said:

The Starship Pedants are not about guns&insects, they are about teens with guns in stylish uniform and their hierarchical problems. I still can't get, what kind of troops they are.

Ugh. The starship troopers in the film did not come across well from the book.

In the book they were deployed by drop pod from orbit, wore powered armour, had proper communication and other battlefield awareness gear and were armed with everything from flamethrowers to tactical nuclear rockets as required. They were essentially badS sci-fi paratroopers, sent in to do what infantry does best: take ground, hold it and deprive the enemy of it. Because sometimes turning said ground into radioactive glass from orbit doesn't really further your strategic goals.

In the film... yeah what you said.

[kerbiloid]

In the book both races had exoskeletons.

In the movie only the weakest ones.

[Nuke]

plasma as a warhead might be a thing. i recall there being a mention of plasma torpedoes in the expanse books, better than conventional but not quite nuclear. 

[DDE]

2 hours ago, Nuke said:

plasma as a warhead might be a thing. i recall there being a mention of plasma torpedoes in the expanse books, better than conventional but not quite nuclear. 

Quote

In The Expanse occasionally torpedoes are described as using "Plasma Warheads". It is not explained though whether this is idiosyncratic naming or relates to their function.

Trying to add thermal damage on top of raw kinetic is... odd.

 

[magnemoe]

1 hour ago, DDE said:

Trying to add thermal damage on top of raw kinetic is... odd.

 

Yes, your kinetic energy in space tend to be higher than any chemical energy you can add, with fusion powered ships that would always be the case. 

[kerbiloid]

8 hours ago, Nuke said:

plasma as a warhead might be a thing. i recall there being a mention of plasma torpedoes in the expanse books, better than conventional but not quite nuclear. 

Technically, this is a plasmagunner.

Spoiler

He uses pure cold plasma to accelerate unguided kinetic projectiles, but as well can throw his plasma bags like plasmatic grenades.

5 hours ago, DDE said:

Trying to add thermal damage on top of raw kinetic

makes not much sense at least because a plasma package interacts with armor much better than photons (doesn't pierce, doesn't get reflected).

Hitting armor with a plasma cloud makes no sense, comparing to directional hit of any kind, as most part of energy will just dissipate around.
(As well, casting of fireballs is a useless loss of mana on visual effects.)

When a beam hits the surface of hull, it heats a thin spot of material and evaporates it, turning into a pancake of plasma, like this part of armor was anexplosive itself and just exploded.
This plasmacake expands and damages other armor around, making a wider hole, pushing melted metal from behind inside the room, and spreading hot metal droplets inside the hull.

This lasts for negligible time, so no significant heat can be trensferred, and the weapon is not thermal but purely mechanical (like with HEAT projectiles). Any heating is just a secondary effect.

As a particle beam releases its energy in a thin layer of material, unlike Xray or gamma, and doesn't get reflected like visual photons, it's the most efficient way to make the target's armor burst and damage the inner structures.

So, see above about hydrogen beams.

If you need visual effects, the hydrogen atoms still have various thermal speed inside the jet, so the jet will expand a little and get the shape of spindle or comet.
As it's hot, it will glow. So, you have a rationale for pew!-pew!-pshh!-pshh! like on the OP picture.

Edited July 4, 2020 by kerbiloid

[Spacescifi]

To be sure I have no intention of using the bullet scifi plasma fireballs, but I am OK with using a rapid fire version of the 3% speed of light plasma rings humans claim they experimented with.

May just upgrade it to 10% speed of light... because scifi.

Lots of plasma splash.

Useful for disabling sensitive communication satelites and sensors.

A poor ship killer, but can sure wreck sensor arrays with X-rays when the plasma hits them.

Realistic plasma weaponry is auxiallary at best, optional at least, and not even necessary at worst.

Edited July 4, 2020 by Spacescifi

[kerbiloid]

Any splash is a waste of energy.

[KerikBalm]

On 7/2/2020 at 11:39 PM, WestAir said:

It always bothered me that sci fi writers go straight for the rule of cool instead of being an inspiration to real world researchers. Lasers, plasma swords and shields all look shiny, but IMO more sci fi writers should go for sensible and unique countermeasures ... Lasers being defeated by mirrors or radiators.

Lasers are perfectly practical, and are seeing real world use. Also, when it comes to space ware fare in particular, mirrors won't defeat them.

 

We're used to mirrors and visible light, but there are many problems with using mirrors for defense against lasers, in increasing importance:

#1) Your signal return goes way up, you are now easily visible for attack by other methods. Any thanks to mirros adding mass, there's less to be done about it.

#2) You can't cover everything in mirrors, sensors, radiations, etc. What isn't covered can leave you blinded or disabled

#3) 99% reflective is still enough for a concentrated laser to damage the surface, rapidly decreasing the reflectivity, destroying the mirror. The laser focusing array may use mirrors, but in a parabpolic dish to focus the beam, so you have a wide area concentrating to a narrow one. Keeping your whole ship shiny in space with space dust impacts and solar wind damage will prove to be a very difficult task

#4) Mirrors don't work across the entire EM spectrum. If you are in a space battle, and being targetted by an UV or "soft" X ray laser, mirrors only reflect at very low angles. This is a problem for focusing the laser, requiring "grazing incidence mirrors", but since they only need to be oriented one way, and X ray lasers can reach ridiculous ranges (so you won't need to turn fast to track a target), this works in the attacker's advantage, since a defender could only use "mirror armor" to defend from attacks coming from a very narrow cone. 2 ships with X ray lasers sufficiently spaced apart? your mirrors won't work against both of them. Also your mirrors need to be smooth down to the atomic level... good luck.

And if we did "hard" X ray and gamma ray lasers? good luck. Mirrors don't work against those, you need strained diffraction gratings. It would be very hard to make a focused hard X ray laser, but then the range would be obscene, and no form of mirror would protect you. You couldn't use a similar diffraction grating to protect yourself, because of point 3- the ratio between the area of focused beam spot on the target vs the area  of the focusing apparatus. Point 3 is the only way your could hope ot make a gamma ray laser work, because the only way to focus them is using a zone plate http://panoptesv.com/SciFi/LaserDeathRay/ZonePlate.html which will result in your focussing array absorbing half the energy output of your laser (so if the gamma ray generation is 50% efficient, and your focusing array is 50% efficient, then firing the laser heats your ship up 3x more than the target ship, your only hope is that your radiators are sufficient to handle the energy output, and you can cause explosive effects on the target because the energy is more concentrated on the target.

http://panoptesv.com/SciFi/LaserDeathRay/Mirrors.html

http://panoptesv.com/SciFi/LaserDeathRay/GrazingIncidenceMirror.html

http://panoptesv.com/SciFi/LaserDeathRay/VUV.html

http://panoptesv.com/SciFi/LaserDeathRay/SoftX.html

http://panoptesv.com/SciFi/LaserDeathRay/HardX.html

http://panoptesv.com/SciFi/LaserDeathRay/Gamma.html

On 7/3/2020 at 12:33 AM, Spacescifi said:

Assuming the plasma balls can hold for any sufficient amount of time you could fire of beads of plasma and do a bunch of thermal burning.

The only real advantage over lasers that plasna balls have that don't dissipate is that they don't lose much energy, so they will do more thermal damage than a laser... if they hit.

This is just wrong:

Plasma emits a lot of blackbody and brehlmstrahlung radiation. Plasma will rapidly cool. Any sort of internal magnetic field ot make a plasma vortex will weaken, the plasma will become more diffuse. Lasers won't dissipate energy until after the range is beyond their diffraction limited focal distance.... which if we're talking X rays and focal arrays of just 10's of meters in diameter... can be measured in the AUs.

Also, plasma may be hot, but its also not very dense, a miniscule amount of very hot matter still won't contain all that much heat. A plasma bolt with some internal magnetic field confinement won't be very dense.

On 7/3/2020 at 1:13 AM, Dragon01 said:

TBH, if you want "lasers", your best bet is actually railguns, funnily enough.  A typical weapons-grade railgun would heat the projectile to incandescence, and it would look a lot like a tracer round, which themselves look a lot like a Star Wars-style laser bolt. Space battles using high velocity railguns could very well be quite spectacular.

Yea, a laser in space wouldn't be visible. In air, its normally not visible unless there's a lot of particulate matter in it (fog, smoke), which will dramatically decrease range. A laser battle would just have some light at the muzzle of the attacker (from less than 100% efficient specular reflection of the focusing apparatus), and a bright light on th target as it either vaporizes, or melts.

If its a pulsed laser, you essentially just have an explosion on your target surface... and such a method is more efficient than slowly melting through the target.

http://panoptesv.com/SciFi/LaserDeathRay/AspectRatio.html

http://panoptesv.com/SciFi/LaserDeathRay/DamageFromLaser.php

 

On 7/3/2020 at 9:46 PM, KSK said:

Ugh. The starship troopers in the film did not come across well from the book.

In the book they were deployed by drop pod from orbit, wore powered armour, had proper communication and other battlefield awareness gear and were armed with everything from flamethrowers to tactical nuclear rockets as required. They were essentially badS sci-fi paratroopers, sent in to do what infantry does best: take ground, hold it and deprive the enemy of it. Because sometimes turning said ground into radioactive glass from orbit doesn't really further your strategic goals.

In the film... yeah what you said.

The film was basically a parody of the jingoistic/hyper-milataristic viewpoint of Heinlein, who expressed disdain for civilians that didn't do military service.

Both the book and film have this idea that you should serve in the military to be a full citizen/ have a say in government. Heilein seems to really believe if you're not willing to fight for your country, you don't deserve a voice in how its run.

The film seems to parody this idea, and portrays it as some pretty ridiculous fascism.

Edited July 6, 2020 by KerikBalm

[DDE]

3 hours ago, KerikBalm said:

The film was basically a parody of the jingoistic/hyper-milataristic viewpoint of Heinlein, who expressed disdain for civilians that didn't do military service.

Both the book and film have this idea that you should serve in the military to be a full citizen/ have a say in government. Heilein seems to really believe if you're not willing to fight for your country, you don't deserve a voice in how its run.

The film seems to parody this idea, and portrays it as some pretty ridiculous fascism.

SST falls on its face for many reasons. One of them being the director's lack of dedication to deconstructing Heinlein's premise, assuming that its mere depiction is automatically repugnant - perhaps to someone who thinks a traffic ticket is a microfascism it is.

But, more amusingly, its attempt to ridicule militarism through gung-ho tactics fails because sci-fi tactics (specifically their absence) are impossible to parody.

[kerbiloid]

I was thinking, it's about bugsquashing...

Or debugging.

***

Who rules the Heinlein's Martians? (those slimy unhuman ones)

Have they served in the military? If no, why? Haven't they become so ugly and unhuman because hadn't?

Edited July 6, 2020 by kerbiloid

[wumpus]

 

6 hours ago, KerikBalm said:

 

Both the book and film have this idea that you should serve in the military to be a full citizen/ have a say in government. Heilein seems to really believe if you're not willing to fight for your country, you don't deserve a voice in how its run.

 

The film seems to parody this idea, and portrays it as some pretty ridiculous fascism.

You had to serve in the *government*.  This should have been clear in the book and was repeated by RAH plenty of times.  Of course, if you sign a hitch in the government, there is always the chance that after your physical you will get slotted as 11b (infantryman MOS) instead of census records sysadmin.

The bit about limiting a franchise to those willing to fight was quite true, just limiting it to those who actually fought.

RAH seemed to like the idea of a "opt-in" social contract, often with areas designated for those who "op-out".  Requiring some sort of service beyond "opting in" goes even further. 

1 hour ago, kerbiloid said:

Who rules the Heinlein's Martians? (those slimy unhuman ones)

Have they served in the military? If no, why? Haven't they become so ugly and unhuman because hadn't?

The Old Ones.  And I'm pretty sure the Old Ones were the ones that destroyed the planet formerly between Mars and Jupiter.  The living were neither consulted nor likely needed.

- Note I don't recommend taking his post-stroke attempts to unify works meant to stand on their own.  And as far as I can tell, it seemed like a short-lived fad among old authors at the time.

PPS:  For a better way to counter Starship Troopers, see Joe Haldeman's Forever War.  Same basic book, except one was written by a career naval officer who was kick out due to a medical condition before Pearl Harbor, the other was drafted into Viet Nam, and set off airport metal detectors thanks to carrying too much sharpnel even before 9/11.

Edited July 6, 2020 by wumpus
read more of the thread

[KSK]

1 hour ago, wumpus said:

You had to serve in the *government*.  This should have been clear in the book and was repeated by RAH plenty of times.  Of course, if you sign a hitch in the government, there is always the chance that after your physical you will get slotted as 11b (infantryman MOS) instead of census records sysadmin.

It's mentioned near the start of the book. Federal service is either a term in the military or "a most unreasonable facsimile thereof." It's also mentioned that the government *has* to allow you to serve as your constitutional right and has a lot of dirty and dangerous 'make work' alternatives to army or naval service because most of the volunteers for such service are either not needed or not suited for it. Also, 'military service' can vary quite wildly. We see this later in the story where Rico encounters a former boot camp cadet who washed out on medical grounds and was now serving as third cook aboard a troop transport.

1 hour ago, wumpus said:

PPS:  For a better way to counter Starship Troopers, see Joe Haldeman's Forever War.  Same basic book, except one was written by a career naval officer who was kick out due to a medical condition before Pearl Harbor, the other was drafted into Viet Nam, and set off airport metal detectors thanks to carrying too much sharpnel even before 9/11.

I have a feeling that the Ender's Game series was also a counter to Heinlein's notion that intelligent species will necessarily compete, with the stronger wiping the weaker out. Unsure where I read that though so take with a pinch of salt.

4 hours ago, DDE said:

SST falls on its face for many reasons. One of them being the director's lack of dedication to deconstructing Heinlein's premise, assuming that its mere depiction is automatically repugnant - perhaps to someone who thinks a traffic ticket is a microfascism it is.

Agreed. I saw the film before reading the book and came very close to walking out because it was just bad - and not even in a campy 'so bad it was good' sort of way. Having read the book, I can see what the film was trying to be but IMO it came across as a lazy, clumsily executed mess of a parody.

Although in fairness, I think that doing a good Starship Troopers film would be very difficult. Doing it as a straightforward military sci-fi adventure and leaving out all the political philosophy would be pretty controversial and treating the politics seriously, whether that's to deconstruct them or otherwise, could easily result in a fairly indigestible film. 

[WestAir]

20 hours ago, KerikBalm said:

Lasers are perfectly practical, and are seeing real world use. Also, when it comes to space ware fare in particular, mirrors won't defeat them.

Aye. KSK already shot down my entire comment, including my false statement on lasers, a few comments back:

On 7/3/2020 at 3:59 AM, KSK said:

Defeating lasers with mirrors is an old trope that doesn't bear up too well in real life.

 

[kerbiloid]

If somebody could make non-material lenses, he could make non-material mirrors.

So, if somebody makes a field interacting with photons, he could build supertelescopes and cloaked cruisers with mirroring armor.

[KerikBalm]

2 hours ago, WestAir said:

Aye. KSK already shot down my entire comment, including my false statement on lasers, a few comments back:

 

Well, he basically only said that mirrors won't reflect 100% of the light, and thus can fail.

He didn't bring up that against the wavelengths that youou would want to use in space, mirrors just won't work at all.

[DDE]

5 hours ago, kerbiloid said:

If somebody could make non-material lenses, he could make non-material mirrors.

So, if somebody makes a field interacting with photons, he could build supertelescopes and cloaked cruisers with mirroring armor.

There are sporadic mentions of using lasers to manipulate the optical properties of air to further facilitate their end use.

Combat-oriented lasers.

[kerbiloid]

Yes. but I mean in vacuum. Some magic photomagnetic field.

[DDE]

5 hours ago, kerbiloid said:

Yes. but I mean in vacuum. Some magic photomagnetic field.

Please. I only use natural substances like degenerate matter for all my light-bending needs.

[kerbiloid]

33 minutes ago, DDE said:

Please. I only use natural substances like degenerate matter for all my light-bending needs.

Technically, the elementary particles, interacting with photons, are not hard balls of steel, they are clots of... something... fields, momentum, and energy.

So, why a developed civilisation could not generate something like that, too.

[Superfluous J]

This thread has convinced me to not use Plasma as my generic sci-fi weapon in my realisticish space opera fiction.

Instead my blasters will fire Aether.

[kerbiloid]

And aethereal scoops.

[K^2]

On 7/2/2020 at 1:56 PM, Scotius said:

It might be the only way to create actually useful plasma weapons. IF someone finds a way to keep plasmoids from rapidly dissipating in the vacuum.

Not sure that's necessary. A near light-speed beam is not going to diverge a whole lot. You can either think of it as relativistic effect or as magnetic field generated by the plasma current. Either way, with enough energy, there just isn't enough time in proper frame for plasma to dissipate. I don't know if there is any advantage whatsoever over just lobbing a projectile, but making plasma beam weapons is actually way more plausible than you'd normally think.

[WestAir]

3 hours ago, K^2 said:

Not sure that's necessary. A near light-speed beam is not going to diverge a whole lot. You can either think of it as relativistic effect or as magnetic field generated by the plasma current. Either way, with enough energy, there just isn't enough time in proper frame for plasma to dissipate. I don't know if there is any advantage whatsoever over just lobbing a projectile, but making plasma beam weapons is actually way more plausible than you'd normally think.

"They blew up our planet!"

(gasp) "Impossible! What frightening technological marvel could do such a terrible thing?"

"Well... They kinda just threw a baseball at relativistic speeds."

"Oh."

[magnemoe]

7 hours ago, K^2 said:

Not sure that's necessary. A near light-speed beam is not going to diverge a whole lot. You can either think of it as relativistic effect or as magnetic field generated by the plasma current. Either way, with enough energy, there just isn't enough time in proper frame for plasma to dissipate. I don't know if there is any advantage whatsoever over just lobbing a projectile, but making plasma beam weapons is actually way more plausible than you'd normally think.

You could anyway just add electrons on exit, now we are annyway talking about an particle accelerator gun (forgot the real name)

An sci-fi spaceship will have one plasma weapon, its drive. Any sort of fusion drive, orion or advanced fission like gas core will produce plasma as reaction mass. 
That is an serious output but not something who is very useful as an weapon even at artillery range unless you have some extremely large engine. 
But it would make an impressive close in weapon, pretty sure you could add stuff to the plasma to make it an more effective weapon or shape part of the exhaust to target missiles. coming towards you. 

In most settings missiles will come from your front arch, to use the drive you need to turn around and trust. This is just to use the drive flame as an weapon and obstacle not so much to dodge and you are unlikely to run away. 
This leaves another problem you has to target missiles trough your own exhaust. This can probably be mostly resolved dropping off some screening drones who will both target the missiles themselves and act as forward observers for the ships own guns. 

The problem with using the drive this way is that you expose the vulnerable drive who can not be armored unlike the front of the ship.