"High-Powered" Plasma Drives

[Simon_Jester]

Well, in-setting, power generation for ships is onboard fusion reactors; a good set of anywhere from two to six will give you up to a terawatt of usable power, less waste heat. Factoring in other inefficiencies, and the requirements of the electric propulsion, then weapons, which tend to be laser armament, is going to be sub-kiloton range.

Assuming you've got enough power to run your drive at those levels... that's sub-kiloton per second, Whiskey.

Now tell me, what could ten minutes' sustained fire from the ship's main battery do?

EDIT: about how damaging would a group of 4 drives producing 16.5 meganewtons be, with an top exhaust velocity of 100,000 km/s? Doing out the math, a mass ratio of only three would be required for a delta-v of around 110,000 km/s. Not too shabby, though it's probably a whole lot more than is necessary.....

Tremendously so. Unless your FTL system is really, really strange, there is no reason to have such a high delta-v. And great reasons for civil society to bar people from using ships with such a high delta-v: they have a lot of potential as missiles.

Also. Calculate the momentum of the exhaust cloud the ship's drive releases in one second, based on how much force it applies to the ship. From there, you can calculate the mass ejected using the known exhaust velocity, and thus calculate the energy output of the drive.

You tell me what it works out to.

[Whiskey144]

Assuming you've got enough power to run your drive at those levels... that's sub-kiloton per second, Whiskey.

And this is why I post here. I get the clarifications I need to tell me thinks I haven't thought about. Though that's also a very good point.

Now tell me, what could ten minutes' sustained fire from the ship's main battery do?

I'm going to simply guess and say "nuke-level+" damage.

Tremendously so. Unless your FTL system is really, really strange, there is no reason to have such a high delta-v. And great reasons for civil society to bar people from using ships with such a high delta-v: they have a lot of potential as missiles.

Well, the FTL system is an Alderson-point derivative, at its most basic. It's probably more analogous to EVE Online's system of jumpgates (in fact, that's the inspiration I took from), though ships lack warp drives, excepting military vessels and one-offs that a particularly wealthy mercenary, trader, or pleasure yacht might have. Or something a pirate steals, I suppose.

I've actually done the math out; with the given ship mass, I can actually move to a truly ludicrous mass ratio of 1.5, while still reducing exhaust velocity by a factor of 2, and have around 25,000 km/s of delta-v. Still a lot more than is strictly necessary, methinks.

OTOH, I'm still on the fence with whether or not the warp drive I'm going to include will require the main drives to operate a la Mass Effect, or whether it will be a self-contained system.

Also. Calculate the momentum of the exhaust cloud the ship's drive releases in one second, based on how much force it applies to the ship. From there, you can calculate the mass ejected using the known exhaust velocity, and thus calculate the energy output of the drive.

Hmm. I'm not sure I quite follow what you're saying here; I found an equation that gives rocket thrust force as a function of exhaust velocity multiplied by mass flow, and given that on the ship in question there are 4 drives operating, I got about 1.5 kg/s mass flow per drive unit. About 6 kg/s total mass flow. It's ejected at 100,000 km/s, for a good 150 million kg*m/s of momentum........but I've no idea where to proceed from there.

You tell me what it works out to.

At this point, it's looking like, "it's a lot, and wastefully, excessively, more than is even generously required".

[Simon_Jester]

Assuming you've got enough power to run your drive at those levels... that's sub-kiloton per second, Whiskey.

And this is why I post here. I get the clarifications I need to tell me thinks I haven't thought about. Though that's also a very good point.

Now tell me, what could ten minutes' sustained fire from the ship's main battery do?

I'm going to simply guess and say "nuke-level+" damage.

Estimate weapon power output in watts. Watts are joules per second. Multiply by number of seconds.

Obviously, 100 terajoules of laser fire will not have the same effects on a target as a single nuclear blast that releases 100 terajoules of energy by fission. Arguably, 100 terajoules of laser fire would be worse, because they can be targeted more precisely: one nuke can destroy only one relatively limited area, whereas lasers fired from a few hundred kilometers up could conceivably burn every strategic target within a hundred kilometer radius.

Some of this is high school physics stuff, just applied and with large numbers. I recommend you review The Cartoon Guide to Physics, by Larry Gonick, to get a basic grasp of the relationships at work here- in particular, coming to understand the relationship between momentum, force, energy, and power is very important if you're seriously trying to calculate this stuff.

Well, the FTL system is an Alderson-point derivative, at its most basic. It's probably more analogous to EVE Online's system of jumpgates (in fact, that's the inspiration I took from), though ships lack warp drives, excepting military vessels and one-offs that a particularly wealthy mercenary, trader, or pleasure yacht might have. Or something a pirate steals, I suppose.

How far apart are the Alderson points?

[I'm a mild fan of the original CoDominium setting featuring the Alderson drive, for which Alderson himself was the physics consultant]

This is important- if Alderson points are located around the orbit of Mars, or close to a planet, there is no good reason for starships to need more than, oh, a few thousand km/s of delta-v. Probably less than that- consider that at 0.01g, it takes something like three hours to change your velocity by one km/s. You won't have time to use that much delta-v before you reach and overtake your target. Trip times will be measured in weeks, like the Age of Sail- but men can build, and have built, civilizations knit together by vessels that moved at that pace.

If the Alderson points are located around the orbit of Neptune or so, the distances that must be covered in sublight are larger. Ships spend even more time covering those distances, and the incentive to build higher-acceleration drives gets larger, as does the incentive to build ships with more total delta-v.

In the CoDominium setting, ships spend an enormous amount of time running on ~1g torch drives because the Alderson points are that far out, more or less.

Also. Calculate the momentum of the exhaust cloud the ship's drive releases in one second, based on how much force it applies to the ship. From there, you can calculate the mass ejected using the known exhaust velocity, and thus calculate the energy output of the drive.

Hmm. I'm not sure I quite follow what you're saying here; I found an equation that gives rocket thrust force as a function of exhaust velocity multiplied by mass flow, and given that on the ship in question there are 4 drives operating, I got about 1.5 kg/s mass flow per drive unit. About 6 kg/s total mass flow. It's ejected at 100,000 km/s, for a good 150 million kg*m/s of momentum........but I've no idea where to proceed from there.

What is the formula for kinetic energy? Use it to get the kinetic energy that goes into the exhaust plume per second. You will be surprised, and it may affect your notion of how much power your ships need to make the drive work...

Go on. Tell me what the number works out to.

[SpaceMarine93]

Here's one from Revelation Space:

Conjoiner Drive

Conjoiner drives are starship engines that use quantum mechanics to propel starships up to relativistic speeds, giving such ships the name "lighthuggers". It is at one point said that Conjoiner drives contain a small wormhole linked to the very deep past, through which they draw their propulsion energies from the Quark-gluon plasma created by the Big Bang.

A small part of the workings of the drives is revealed in Galactic North. The drive has six manual control dials that allow the power of the drive to be varied. As the drive power is increased, so does the risk of an uncontrolled, ship destroying explosion. Lighthuggers mount a pair of Conjoiner drives, both of which are controlled by a disembodied Conjoiner brain that performs rapid calculations to control the internal drive reactions. If the turbulence within the drive exceeds the ability of the brain, the drive will explode. The drive is also designed to explode if non-Conjoiners attempt to open it for reverse engineering, or if the gap between two drives on the same ship grows too large. This occurs because the Conjoiner brain is housed within one of the engines and controls the other remotely; once the other drive passes out of the brain's control, the internal reactions quickly spiral out of control.

[Whiskey144]

Estimate weapon power output in watts. Watts are joules per second. Multiply by number of seconds.

*fistpalm, because facepalm does not express my fail*

Once again, demonstrating just why I ask questions here.

How far apart are the Alderson points?

Well, there not exactly Alderson points, but they tend to actually be all over the place. Each "point" is actually a large, megastructure-sized 'jumpgate'. Each gate connects to only one other gate, but obviously allows 2-way travel between the two, though there are exceptions in that there are enormous (2-3x bigger than normal) gates that are massive 'hubs', and connect to many other gates.

So in this case, the gates vary between orbiting very close (inside Earth orbit) to very far (Kuiper belt). OTOH, military vessels also mount a warp drive and large capacitor bank (power plants 'of the day' can't supply the power necessary for the warp drive), so for a military warship, really long distances are fairly irrelevant.

What is the formula for kinetic energy? Use it to get the kinetic energy that goes into the exhaust plume per second. You will be surprised, and it may affect your notion of how much power your ships need to make the drive work...

I think it has, very, very much so.

Go on. Tell me what the number works out to.

Yeah, it worked out to 60 petawatts. The fusion plants barely produce power in the single-digit terawatt range.

So I now have a problem, whose solution is probably to reduce acceleration by another OOM. Which means I only need about 1.6 meganewtons of thrust force, and which reduces engine power to requiring "only" about 83 terawatts. So a good three OOM-reduction in engine power requirements. And still an OOM more than the fusion plants can produce.

I'm all out of ideas on how to get this down while still getting usable amounts of acceleration.

EDIT:

Here's one from Revelation Space:

Oh, I'm well aware of RevSpace's Conjoiner Drives. However, for my setting they don't fit, at all. A MAJOR stylistic component of the story has to do with engines requiring remass. Conjoiner-drive analogues would represent a propulsion revolution in-setting.

[Simon_Jester]

Here's one from Revelation Space:

Conjoiner Drive
Conjoiner drives are starship engines that use quantum mechanics to propel starships up to relativistic speeds, giving such ships the name "lighthuggers". It is at one point said that Conjoiner drives contain a small wormhole linked to the very deep past, through which they draw their propulsion energies from the Quark-gluon plasma created by the Big Bang...

...In other words, it's a handwavium drive that works by technobabble. Whereas we are talking about actual rocket engines, albeit improbably impressive ones.

SM93, I must ask you to not clutter up the discussion with random descriptions of magic engines that are of no use to Whiskey.

Go on. Tell me what the number works out to.

Yeah, it worked out to 60 petawatts. The fusion plants barely produce power in the single-digit terawatt range.

So I now have a problem, whose solution is probably to reduce acceleration by another OOM. Which means I only need about 1.6 meganewtons of thrust force, and which reduces engine power to requiring "only" about 83 terawatts. So a good three OOM-reduction in engine power requirements. And still an OOM more than the fusion plants can produce.

I'm all out of ideas on how to get this down while still getting usable amounts of acceleration.

Basically, you need drives with lower exhaust velocity- a reaction drive that works by throwing material overboard at relativistic speeds is going to be an insane power hog almost by definition. Compare your drive to existing ion thrusters, which consume roughly fifty kilowatts per newton of thrust- closer to what you need to make these things work.

The problem is that to get that you have to eject more propellant for a given delta-v, which means higher mass fractions and/or lower delta-v. Lower delta-v will make reaching jumpgates in the far corners of the system significantly inconvenient and require a pretty serious effort devoted to refueling.

Oh, and when calculating delta-v, you are using the Tsiolkovsky rocket equation, or something similar, from Atomic Rocket or elsewhere, right?

Remember, a drive that has an exhaust plume carrying six kilograms of ions per second at ~100000 km/s is energetically equivalent to firing a six-kilogram slug at the same speed... every second. Megaton-per-second energy output, on both ends, and an utterly devastating weapon.

[Connor MacLeod]

I think conjoiner drives are reacitonlesss, they just have an effectively external/near-infinte power tap system to get around fuel problems. God knows they use a reaction drive for everything else.

Also, is being pedantic about numbers REALLY that important to a story? consistency is what matters, and you don't really need to be hardcore about the math to be consistent, if you've planned out your setting sufficiently and you use the right wording I don't see how it would be an issue. Numbers can be useful to a point, but too much of it and it will start interfering with other things.

[Beowulf]

As another note: you've mentioned they're powered by fusion reactors. If you're using more hydrogen to fuel your drive than you're tossing out the back end, you're probably on the wrong end up of the fuel efficiency curve, because for propulsion efficiency, you can't just go with what you're tossing out the back end, but the fuel used to move that as well. There are ways around this, such as using solar panels to power the drive, but you'd need giant arrays to supply enough power to give useful thrust, which doesn't work here. If you use more fuel to accelerate the propellant to higher velocity that you could get by just adding the fuel to the mass flow out of the engine, you're probably better off just adding it to the mass flow out of the engine.

[Whiskey144]

Basically, you need drives with lower exhaust velocity- a reaction drive that works by throwing material overboard at relativistic speeds is going to be an insane power hog almost by definition. Compare your drive to existing ion thrusters, which consume roughly fifty kilowatts per newton of thrust- closer to what you need to make these things work.

Yeah, right now, I'm rethinking the whole "33 PSL exhaust velocity is a good idea" thing. I think I'll settle for 1,000 km/s as an upper-limit exhaust velocity on the drives. Much more modest, even if it's less efficient.

The problem is that to get that you have to eject more propellant for a given delta-v, which means higher mass fractions and/or lower delta-v. Lower delta-v will make reaching jumpgates in the far corners of the system significantly inconvenient and require a pretty serious effort devoted to refueling.

For the most part, the jumpgates are in the Mars/asteroid belt orbital region, occasionally getting as close as Venus or as far as Jupiter. Very rarely are they further out or in, and pretty much every case is in a massive "central-station" system of gates, wherein large numbers of gates are present, and generally the gate you want will be close to the gate you came from.

Which is, I'm thinking, something that could be a plot point........OTOH, so could a gate in the Kuiper belt or the Oort cloud. Since the gates, in-setting, are barely understood, they could quite easily be hidden by the original gate-builders in such a region.

I now love my gate system much more than before.

Oh, and when calculating delta-v, you are using the Tsiolkovsky rocket equation, or something similar, from Atomic Rocket or elsewhere, right?

Taken from that page, IIRC.

Remember, a drive that has an exhaust plume carrying six kilograms of ions per second at ~100000 km/s is energetically equivalent to firing a six-kilogram slug at the same speed... every second. Megaton-per-second energy output, on both ends, and an utterly devastating weapon.

And one which would outmatch all others in-setting. Not good, to say the least.

Also, is being pedantic about numbers REALLY that important to a story? consistency is what matters, and you don't really need to be hardcore about the math to be consistent, if you've planned out your setting sufficiently and you use the right wording I don't see how it would be an issue. Numbers can be useful to a point, but too much of it and it will start interfering with other things.

See above. Right now, I've got fusion plants that give, at absolute most, a single-digit terawatts; triple-digit gigawatts are far more common. While that's "only" sub-kiloton/second, it's a whole lot less than the megaton/second that the drive I had originally spec'd could spit out.

I think conjoiner drives are reacitonlesss, they just have an effectively external/near-infinte power tap system to get around fuel problems. God knows they use a reaction drive for everything else.

I dunno; looking at a bit in the first novel indicates that the engines have remass.

As another note: you've mentioned they're powered by fusion reactors. If you're using more hydrogen to fuel your drive than you're tossing out the back end, you're probably on the wrong end up of the fuel efficiency curve, because for propulsion efficiency, you can't just go with what you're tossing out the back end, but the fuel used to move that as well. There are ways around this, such as using solar panels to power the drive, but you'd need giant arrays to supply enough power to give useful thrust, which doesn't work here. If you use more fuel to accelerate the propellant to higher velocity that you could get by just adding the fuel to the mass flow out of the engine, you're probably better off just adding it to the mass flow out of the engine.

.....That's a good point, I suppose. I don't really know for sure; I pretty much don't understand nuclear physics, so I'm going to have to pretty much hope someone here knows enough to explain it to me, and hopefully how I might calc the fuel requirements of a fusion reactor.

[Connor MacLeod]

Honestly I think the more you try to focus on "hard numbers" the more problems are going to crop up and the smaller your numbers are going to dwindle. You're probably much better off handwaving to whatever extent you need to and can still retain consistency and leave it at that. Hard Sci fi is good if someone can pull it off, but very few people have the math and science IMHO to pull it off - I know I sure as hell couldn't.

This thread just really feels like it's going toward that "you want to go handwaving rather than hard numbers" route as well. I could be wrong though.

[Simon_Jester]

I think conjoiner drives are reacitonlesss, they just have an effectively external/near-infinte power tap system to get around fuel problems. God knows they use a reaction drive for everything else.

Also, is being pedantic about numbers REALLY that important to a story? consistency is what matters, and you don't really need to be hardcore about the math to be consistent, if you've planned out your setting sufficiently and you use the right wording I don't see how it would be an issue. Numbers can be useful to a point, but too much of it and it will start interfering with other things.

Well, if he can get an internally consistent set of figures for the performance parameters- mass fraction, time taken to travel a given distance, shipboard power output- that's all to the good. So fiddling around with this is probably worth the effort up to a point; done carefully it creates story opportunities rather than destroying them.

At some point, Whiskey will start waving his hands again, probably when he has to worry about waste heat. But having an internally consistent set of constraints imposed on his ships by the rocket equation will allow him to define his own setting more rigorously- ships take time to travel, time is related to distance, there are a variety of ways to get where you're going faster but they have costs and tradeoffs, and so on.

So I approve, as long as he doesn't let the math choke his ability to write the setting.

As another note: you've mentioned they're powered by fusion reactors. If you're using more hydrogen to fuel your drive than you're tossing out the back end, you're probably on the wrong end up of the fuel efficiency curve, because for propulsion efficiency, you can't just go with what you're tossing out the back end, but the fuel used to move that as well. There are ways around this, such as using solar panels to power the drive, but you'd need giant arrays to supply enough power to give useful thrust, which doesn't work here. If you use more fuel to accelerate the propellant to higher velocity that you could get by just adding the fuel to the mass flow out of the engine, you're probably better off just adding it to the mass flow out of the engine.

Good point. The yield of a fusion reaction is going to be on the order of... I don't know, probably terajoules per kilogram of fuel expended? Eyeball it at... oh how about 30 TJ/kg?

That's an arbitrary, uneducated guess, by the way, based on potential yield and figuring ten-percentish efficiency. Anyone with even slightly more information is invited to step forward. And don't ask me how you manage to radiate off the excess. Aiaiaiai...

For a terawatt reactor that doesn't require particularly unreasonable rates of power consumption, but for a reactor in the petawatt range that can drive this high-velocity exhaust plume, you're shoveling hydrogen into the reactor a lot faster than you're shoveling it out the engines.

Basically, you need drives with lower exhaust velocity- a reaction drive that works by throwing material overboard at relativistic speeds is going to be an insane power hog almost by definition. Compare your drive to existing ion thrusters, which consume roughly fifty kilowatts per newton of thrust- closer to what you need to make these things work.

Yeah, right now, I'm rethinking the whole "33 PSL exhaust velocity is a good idea" thing. I think I'll settle for 1,000 km/s as an upper-limit exhaust velocity on the drives. Much more modest, even if it's less efficient.

It's less efficient in some ways and more so in others. On the one hand you get lower specific impulse, lower delta-v, and higher mass fraction. On the other hand, a lower-velocity exhaust means you burn less fuel in the reactor, and can carry a smaller reactor which means less weight allotted to the ship's drive. (The reactor exists mainly to power the drive, so I consider it part of the drive itself as far as mass considerations go).

Which is, I'm thinking, something that could be a plot point........OTOH, so could a gate in the Kuiper belt or the Oort cloud. Since the gates, in-setting, are barely understood, they could quite easily be hidden by the original gate-builders in such a region.

I now love my gate system much more than before.

And a gate in the extreme outer system could now require extreme-range modifications for a ship to be able to reach- either more fuel tanks or longer endurance, since it isn't practical to just boost the ship up to ten percent of light speed and be there in a few weeks.

[Whiskey144]

It's less efficient in some ways and more so in others. On the one hand you get lower specific impulse, lower delta-v, and higher mass fraction. On the other hand, a lower-velocity exhaust means you burn less fuel in the reactor, and can carry a smaller reactor which means less weight allotted to the ship's drive. (The reactor exists mainly to power the drive, so I consider it part of the drive itself as far as mass considerations go).

On most ships, yeah the reactor is mainly there for drive power, with 'everything else' powered with the 'leftover budget'. OTOH, an armed ship would naturally have a much beefier reactor(s) in order to power its lasers and particle beams and electric cannon.

Of course, I'm perfectly happy to settle for more often refuel timetables; it gives much more incentive to have space stations that are operated as both trade hubs and refueling ports.

And a gate in the extreme outer system could now require extreme-range modifications for a ship to be able to reach- either more fuel tanks or longer endurance, since it isn't practical to just boost the ship up to ten percent of light speed and be there in a few weeks.

An interesting point. Sense story possibilities here, I do.

[Simon_Jester]

On most ships, yeah the reactor is mainly there for drive power, with 'everything else' powered with the 'leftover budget'. OTOH, an armed ship would naturally have a much beefier reactor(s) in order to power its lasers and particle beams and electric cannon.

Heh. Well, if you go for anywhere near the kind of exhaust velocities you were thinking about earlier, the reactor output needed to power the drive at peak acceleration is more than enough to run any kind of onboard energy weapon necessary to deal with the kind of ships you've got around (this being a hard-ish setting, without ridiculously cranked up shields like SW-calc-verse or similarly cranked up material science).

Of course, I'm perfectly happy to settle for more often refuel timetables; it gives much more incentive to have space stations that are operated as both trade hubs and refueling ports.

Though midcourse refueling of ships is a bad thing; it enormously increases the time taken to make the trip, and doubles the total fuel consumption of the voyage. Much better to simply burn up to speed, then coast until you can make your deceleration burn to stop at the destination.

[Whiskey144]

Heh. Well, if you go for anywhere near the kind of exhaust velocities you were thinking about earlier, the reactor output needed to power the drive at peak acceleration is more than enough to run any kind of onboard energy weapon necessary to deal with the kind of ships you've got around (this being a hard-ish setting, without ridiculously cranked up shields like SW-calc-verse or similarly cranked up material science).

Yeah......armor tends to be on the more realistic side, though with shields a ship is generally a tougher nut to crack- OTOH, ship destruction is extremely rare. After all, a properly made fusion reactor is very unlikely to explode in such a way as to totally destroy a ship. Instead, a ship is usually 'hulked' or crippled, somewhat similar to 40K. In the former case, its weapon systems have been sniped off, and its either the navigation sensors or the drives themselves damaged to the point of being unusable.

Though midcourse refueling of ships is a bad thing; it enormously increases the time taken to make the trip, and doubles the total fuel consumption of the voyage. Much better to simply burn up to speed, then coast until you can make your deceleration burn to stop at the destination.

TBH, I was thinking more of a continuous-acceleration course, but that's more due to the low acceleration of the drives requiring a lot of time to get up to convenient velocities. But yeah, midcourse refueling would tend to be bad, unless you're topping up before (or after) you head through a gate.

[Simon_Jester]

Presumably you have to decelerate to (more or less) a halt relative to the gate to pass through safely? If so, you lose the penalty for mid-course refueling, since you're committed to stopping anyway.

[Whiskey144]

Presumably you have to decelerate to (more or less) a halt relative to the gate to pass through safely? If so, you lose the penalty for mid-course refueling, since you're committed to stopping anyway.

That's correct. However, no power has figured out a way to attach anything to the gates themselves. OTOH, said gates are typically in orbit of moons or planets (usually at L4/L5 points due to the gravitational stability), and the stations are usually constructed in similar orbital areas.

Somewhat unrelated to the discussion at hand, but how useful do you think, say, a spinal-mount laser cannon or particle beam be given the (far) lower-powered propulsion systems I've described?

[Simon_Jester]

That's correct. However, no power has figured out a way to attach anything to the gates themselves. OTOH, said gates are typically in orbit of moons or planets (usually at L4/L5 points due to the gravitational stability), and the stations are usually constructed in similar orbital areas.

Wherever the gate is located, there too you can place a fuel depot.

Somewhat unrelated to the discussion at hand, but how useful do you think, say, a spinal-mount laser cannon or particle beam be given the (far) lower-powered propulsion systems I've described?

If you don't mind being unable to fire the gun while accelerating at an angle to your line of fire, I see no problem with this. Particle beam weapons work much better with long acceleration lines, so spinal mounts are all the more likely to be the way to go.

[Whiskey144]

Wherever the gate is located, there too you can place a fuel depot.

I think we're saying the same thing, with the caveat that I mentioned that nobody knows just how to go about attaching something to the jumpgates themselves.........in part because, in-setting, the jumpgates predate the extant polities and civilizations, and are barely understood. It's somewhat similar to the ME-verse and its Mass Relays, with the caveat that they have a 40K-style understanding of it; they don't really understand how it works, but they can, with time and resources, build more.

I'll also note that jumpgates have no religious terminology attached to them, just to be clear.

If you don't mind being unable to fire the gun while accelerating at an angle to your line of fire, I see no problem with this. Particle beam weapons work much better with long acceleration lines, so spinal mounts are all the more likely to be the way to go.

That works quite well actually; for the most part I envision combat as taking place in one of two forms:

1) The combatants slowly maneuver, probably in a inward-spiral, as they try to get close so that, once shields are dropped, they can get a rapid series of killshots, and shoot of enemy weapon mounts/sensors/other vulnerable stuff before the enemy does so to them. This is what would happen between armed merchants or pirate corvettes taking on civil vessels. Pretty much, any combat situation which doesn't involve actual military vessels will look like this.

2) The combatants maneuver in rapid, seconds-long bursts of high thrust, interspersed by coasting periods of several minutes as shots are fired, or the spinal weapons are lined up. This is what a duel between two military vessels would look like, as military warships either carry a supply of antimatter fuel to inject into the plasma stream of their electric drives (<-is this a good idea given the fairly "low" power these drives normally operate at? is it even plausible, assuming sufficient techlevel?), or a dedicated fusion or antimatter torch. Incidentally, mercenary craft carrying (likely illegal) antimatter can usually perform similar maneuvers.

3) This is the kind of thing that would happen very rarely, in comparison to 1&2. Basically, it's a ship with a torch, or 'afterburning' capability, dueling a ship that's limited to the slow spiral-duels of most civil or civil-esque ships.

[Whiskey144]

Ghetto Edit:

On the subject of particle beam weaponry, about how feasible is it to have a particle beam capable of cutting through a not-insignificant amount of armor and structure, to the point of "ship-slicing" (given sufficient time, typically on the order of several tens of seconds, say) with the power levels I've got at present?

As a further point, about how far could a neutral-charge beam strike a target with reasonable lethality, to at least cut through the kinds of materials that, say, the Space Shuttle uses in its hull?

[hermitbob]

As a further point, about how far could a neutral-charge beam strike a target with reasonable lethality, to at least cut through the kinds of materials that, say, the Space Shuttle uses in its hull?

You mean Styrofoam and china plates? All depends on how many joules you're putting on target. High acceleration allows you to use small particles, but watch out for hard rads when you get to significant portions of c. Don't want to cook your gun crews.

And just a suggestion about your drive, have you thought about a magentosail? I mean it would be better for the short distances(relatively) you're talking about moving your ships, slow as hell though(unless you're willing to burn out your coils).

[Whiskey144]

You mean Styrofoam and china plates? All depends on how many joules you're putting on target. High acceleration allows you to use small particles, but watch out for hard rads when you get to significant portions of c. Don't want to cook your gun crews.

Well, for the most part, I envision these spinal particle beam cannons to be capable of dumping sub-kiloton energies into a target at maximum. Mostly because I'm of the opinion that they'll be fed by capacitor banks fed directly from the main reactor, or in larger warships, from a dedicated plant.

And just a suggestion about your drive, have you thought about a magentosail? I mean it would be better for the short distances(relatively) you're talking about moving your ships, slow as hell though(unless you're willing to burn out your coils).

I'm very attached to the more conventional rocketry concepts.......but I've always considered the idea of carrying a sail-style propulsion backup that you could use to (very slowly) push yourself to somewhere you could fix your broken down ship.

OTOH, I've been looking a bit at negative matter, and contemplating perhaps just handwaving and having negative matter be used in part to drive the plasma through the drives, as well as being used as a counter-grav solution.