What is the diffrence between the two? I have heard references to both in not just Trek but in several games as well. The beams for both look very simular. So what is the diffrence?

Basically, an energy weapon (such as a maser or a laser) emits a tightly focussed beam of energy (microwaves or light). A projectile weapon(such as a pistol or a shotgun) fires off either a missile (a bullet) or a "cloud" of particles (shotgun pellets). When the ammunition for a projectile weapon is a "cloud" of sub-atomic particles, quantum physics effects affect the outcome, and there is almost as much (if not more) similarity to a laser as there is to a shotgun. This is a particle weapon.

Sometimes it is hard to tell if a radiation stream is particulate or energetic. "Radioactive" material can naturally emit three kinds of radiation. Alpha and beta radiation are particle streams. Gamma radiation is energy.

Particle weapons are clumsy but they have uses. Muhahahahaha!

Actually, the term I have seen used is "directed-energy weapons"; this term INCLUDES (A) masers, lasers, X-ray lasers and grasers; (B) particle-beam weapons; and (C) plasma guns, fusion guns, and ion guns. All of these have their advantages and disadvantages. Basically, particle-beam weapons are cyclotrons that you point at the enemy. A CHARGED-particle beam is composed of either positively-charged or negatively-charged particles. Since LIKE CHARGES REPEL, a charged particle beam strong enough to do anything would cause itself to disperse before it could reach any target that isn't already too close. As for a beam of neutrons or other neutrally-charged particles, I have to admit that I don't know enough to comment.

If memory serves, isn't that alpha radiation? Sufficient sheilding would be like a shirt? (I know I'm way off there, I think.)

Just neutrons is not alpha radiation (alpha particles are a Helium-4 nucleus [2 protons, 2 neutrons]).
Neutrons are notoriously nasty, they have a relatively high RBE (~10) and a relatively large penetration depth.

As far as shielding is concerned, keep in mind that a weapons-grade particle beam is going to be coming at you at a high psol (Percent(age) of the Speed Of Light), whereas particles from a bomb or from most natural sources will not be moving very fast. The sole exception to this, THAT I KNOW OF, is cosmic rays, which are mostly SINGLE PARTICLES (alpha or beta) moving at 90-something psol. A weapons-grade particle beam is also of much greater density/intensity than cosmic rays.

To keep any particles focused in a beam don't they need some force on them (even more if they are charged but even neutron difuse by like a factor of four unit per unit traveled [I'm using old highschool stuff from memory here and could be wrong. ])?

Strong a weak neuclear forces are really short range. Magnetism is out if you want to use it near iron cored planets and still be able to aim it. That leaves gravity. If you can control the gravitational attraction that finely do you need particle weapons?

I may be totally wrong, but I think that neutral particles would not diverge that much. Put simply, neutrons, antineutrons, and other neutral particles are the subatomic equivalent of shotgun pellets - which stay close enough together that at a distance of several yards, they can make a single, large-enough hole all the way through a 1-inch-thick board. Incidentally, as for charged particle weapons, you have a small electron gun firing toward your face right now - it's what lights up a picture tube.
As for the effects of a planet's electromagnetic field on a charged particle beam, if your fire control equipment can handle it, you can have the particle beam curve through space - instead of traveling in a straight line - and still hit the target. And since any weapons-grade particle beam would be moving at a high psol, the effect of local gravity will be negligible in most locations.

Mike,

I could be getting mixed up, physics class is way in my past. Doesn't everything if left on its own diffuse or disperse I remember something about the particles (photons or shotgun pelets) spreading out in an area 4 times the distance traveled or something. The range is shorter than say, a rifle (one particle versus say, 20). At some point the rifle is the better weapon. (50 yards or 500 yards I'll take your word for it.) Unless you have something to make the particles "hang out together" your range is going to be short.

To use the electron gun in the CRT as an example, how far away can the screen be from the gun to still phosphoresce(sp?)? If I was in a fight with my computer monitor it could shoot electrons at me all day while I decide what one heavy book I'll throw at it from the next room. (I probably use more energy lifting the book and throwing it that it can use with its puny gun, so this is not a fair fight. [but what good is a fair fight?])

Unless you have something to make the particles "hang out together" your range is going to be short.
Berry

Exactly. This is why a flashlight makes a poor weapon (except as a club), while a laser can be a better one.


But coherence is only one factor, and a small one at that*, that determines the effectiveness of the weapon. As you mentioned, the total mass (and/or energy) makes a big difference as do other factors.

*A laser pointer is not much more effective than a flashlight (unless you shine it directly into someone's eyes.)

Going back to the rifle vs shotgun, the rifle does not has a greater effective range than a shotgun primarily because it has a single projectile, but because the barrel is rifled.

A musket ball travels approximatelty the same distance as a cloud of buckshot before losing enough momentum to no longer be effective. But a bullet fired from a rifle is given a spin from the rifled barrel. This sets up a gyroscopic effect that increases the range.

The thing that makes a laser so effective is the monochromaticity AND the coherence. There is effectively ZERO interference, so all the waves contribute to the beam's amplitude.

>spreading out in an area 4 times the distance traveled or something

That sounds like the famous 'inverse square law' - if you double the distance from the source, you quarter the intensity.

However, that refers to something like a lightbulb, which is generating a diverging light source. That is, the light diffuses because the photons are coming out of the lightbulb in all directions to start with.

In a beam, the particles or photons are collimated, (all moving in parallel straight lines) to start with.

I'm not saying that a neutron beam wouldn't diffuse, as there may be some second-order effects which we haven't considered, but using everyday physics I'd assume the beam would not diffuse.

Thanks Sophie,

I'm still unclear on the rifle versus musket analogy. Discounting lift, drag, and other atmospheric ••••, I thought the spin only kept the projectile on a straighter course. If the musket ball and rifle bullet are machine to allow as little gap between themselves and the barrel (so that no gases can expand without pushing them) why does spin improve the range? (Y.A. Tittle didn't throw toght spirals but his wounded ducks were had the same range as Johnny Unitas's spirals.)

Discounting lift, drag, and other atmospheric ••••, I thought the spin only kept the projectile on a straighter course.

You can't discount atmospheric ****. Spin has to do with atmospheric drag. In a vacuum, it wouldn't matter whether the projectile is spinning or not. Newton's laws apply. However, in an atmosphere, Newton's laws also apply, and atmospheric **** will cause friction, drag, etc..., causing the projectile to change attitude, which will increase drag, slowing the projectile down. Spinning the projectile causes a gyroscopic effect, which tends to keep the bullet/projectile/football oriented in the position of least drag, increasing the range.

Thanks ScottN.

(Gee, I write that a lot.)

Re:Spin as a factor in determining projectile range
The rifle bullet vs musket ball analogy is somewhat incorrect, in that spin is not a factor in range, but the shape of the projectile fired (i.e the length/width ratio of the projectile), which affects the atmospheric drag on the projectile IS
(The Musket ball has a l/w ratio of about 1:1 (It's a Sphere), while the rifle bullet generally has a l/w ratio of 3:1 or greater).
Most modern tank cannon, are Smooth-bore (i.e they have NO Rifling in the barrel) and fire saboted projectiles with l/w ratios of 5:1 or greater).
In this case, the only factor that affects range is the length of the barrel (Expressed in multiples of the projecticle's width (Calibers)).

The rifle bullet vs musket ball analogy is somewhat incorrect, in that spin is not a factor in range, but the shape of the projectile fired (i.e the length/width ratio of the projectile), which affects the atmospheric drag on the projectile IS

On the other hand, the gyroscopic action of the rifling-induced spin does keep the projectile from tumbling (that is, it keeps the long axis of the projectile aligned with the direction of travel, allowing the drag coefficient to remain low, just as Scott said above. It may be relatively minor compared with other effects working on the prjectile, but it does contribute.

Were some muskets ever rifled ?
Then if so, then the rifling-induced spin on the ball could induce lift (on the ball) by means of the Magnus effect, & therefore extend the ball's range, compared to the bullet (I.E effectively the ball's become a rifled bullet with a l/w ratio of 1:1 !)

Muskets
A musket barrel is unrifled, so when it leaves the barrel, the projectile has a random spin from the propellant and any contact with the barrel on its way out - this makes it very inaccurate over range and causes a loss of power over range as well.

With rifling, the projectile spins along its axis of travel, making it closer to a gyroscope along that line. This makes it more accurate at range,and increases the effective range

Rifling a musket would make it a rifle - but the earliest rifles only really differed from the muskets by the rifling - napoleonic era riflemen would set the propellant charge like musketmen, but insert the round wrapped in a small patch of cloth. This gripped the barrel and imparted spin, although meant loading was much slower, as they had to force the round down with their ramrods.
Once the enemy got too close, the riflemen would forget the cloth patches, drop the rounds down the barrel, whack the butt of the gun on the ground to seat the round in the propellant and fire like the musketmen did.

(Never point a loaded musket at the ground, the ball will roll out of the barrel )

For more info, read Bernard Cornwell's Sharpe novels - they may be fiction, but he's done an incredible amount of research (and visited most, if not all of the battle sites).