Screw railguns. This is what I would build with Faey technology.
According to Burnside's Advice: Friends don't Let Friends Use Reactionless Drives In Their Universes.
I might have to add something similar, along the lines that: Friends don't Let Friends Use Torch Drives In Their Universes.
Which is essentially what a PPG is. (If plasma can be phased to make it safe, it can be unphased to make it nice and fun and unsafe, and then you effectively have a Torch Drive.) The problem runs thus:
The short version:
Any fusion reactor can run DT. DT is much more powerful than any other reaction, but is 'dirty' and where possible avoided, because it produces a lot of harmful and normally useless neutrons. DT in fact dumps 80% of its energy into neutrons, which move very fast. Neutrons have mass, but are not and cannot be plasma, and are going to pretty much ignore anything designed to control or repell plasma. They also don't interact with light at all. Though they can be deflected by gravity, and focused by gravitational lenses. Any lightweight fusion reactor is probably going to be gravity contained (in some form) because magnets can't do the job. Thus any fusion reactor can become a weapon of mass destruction.
(Disclaimer: Do not use neutron weapons in an atmosphere.)
Mass is mass. If a single rail-cannon round will do thr trick, so will googleplexes of neutrons.
The long version:
The problem is that light weight fusion plants (especially super light weight PPG style reactors) are very easily converted into small super weapons. Take a standard PPG/generic fusion power core. Adjust it to burn Duterium and Tritium. This is the easiest fusion reaction, and has a power density many order of magnitude higher than any of the others, and especially stellar fusion. Give the containment system two flaws. Flaw A has a 10MeV threashold, meaning particles with less energy can't get through. Flaw B has a 15MeV threashold. Surround the reactor chamber with a 12MeV magnetic gradient. Eighty percent of a DT reactor's energy goes into 14.1MeV neutrons that zip along at 1/5th the speed of light. They'll go through Flaw A with no problem, and won't be affected by the magnetic field. DT also produces lots of 3.5 MeV helium nuclei, which normally wouldn't go through either Flaw, but because they are affected by the magnetic gradient, have enough energy to escape through Flaw B - and can be used for power in all sorts of ways. You now have a very efficient factory of neutrons, which are unaffected by electrical and magnetic fields, have appreciable mass, and are moving at relatavistic speeds.
(Disclaimer: In an atmosphere neutrons scatter in random directions. At these power levels, enough will pull a 180 and hit you; as well as super heating the air, making it explode, and spontaniously setting you on fire.)
The even longer version:
I remember at some point Jason making a trip to the stargate, and the time from Earth's surface to the Stargate (which is in an orbit similar to the Moon) was given as one hour. Plugging this into standard acceleration equations and we get the following:
One hour to the moon / Star Gate
S = 380,000,000 meters = Lunar Orbit
T = 3,600 seconds = 1 hour
A = 117mps2 = 12G
DeltaV = 43 kmps (~Earth’s orbital velocity)
Assume 5 tons
KE = 4,631,104,000,000 = 4.6TJ
PPG Power = 1.3 GW - Or slightly better than the "Mr Fusion" powerplant from the end of Back To The Future.
SI mathematical notation:
0
Kilo 1,000
Mega 1,000,000
Giga 1,000,000,000
Tera 1,000,000,000,000
Peta 1,000,000,000,000,000
Exa 1,000,000,000,000,000,000
E=MC^2. 1kg = 9ExaWatts of energy
I *think* it was Jason't little runabout shuttle that did the trip. I could be wrong about that. I'm also assuming the power system is on the order of a 20cm ‘beer keg’ in size; because we're told the Mech is just as powerful, and there's no much room in the mech for anything larger. If that's wrong there maybe a magnitude error or two in the following:
On a conservative basis:
20cm containment = 1.3 GW = 1.3*10^9
20m containment = 1.3 PW = 1.3*10^15
DT is an easier reaction than whatever the Faey uses = 13PW
Neutron energy is 80% of a DT reactor = 10.4PW
This means we have 39.79 grams of mass @ 1/5th C per second - which represents 1.15 grams of energy per second
In common terms that's roughly 46kT - or slightly more than one Hiroshima per second.
I'm told from various sources that spontaneous conversion of matter to plasma occurs at 10TW to 100TW per meter squared. So what effect would this have? Probably something like a 1,000 mile long lightsabre. Or the Shadow Ship cutting beams from Babylon 5.
More ‘realistic’ power density is 2,500 higher.
DT is an easier reaction = 3.25ExaWatts
Neutron energy = 80% = 2.6EW
= 289.0 grams (energy)
= 5 kilograms (mass) neutrons @ 1/5th C per second
In common terms that's roughly11.6 MT - or slight more than one Terminator 2 'LA Nuke' per second.
[edit:] When I say 'roughly equal to a 10MT bomb' I am reffering to applied power levels, not 'exposure to at range' power levels. If the beam has an area of 25m^2, then a bomb that would produce similar power flux would be 500 tera tons, if it detonated at one kilometer's distance.
[edit 2:] And I seem to have severely underestimated the range. Due to wave/partical duality, you can calculate a point focal length based upon a neutron's 'compton wavelength' - which in weaponised lasers is usually half the range. For a 10 meter lense, this equates to 30trillion kilometers. Of course the neutrons feeding into this lense aren't going to be anywhere near colaminated, but still - even if we half theexponential, we still get a range of about 98million kilometers.
Just saying...