Now for something completely different.
As a common trope of science fiction, we have the presence of energy weapons of a variety of types. Normally given vague names or referred to as lasers, particle beams, plasma, or some other term, they typically have characteristics that don't make any physical sense. What are some of these?
-They move at an incredibly slow speeds, almost to the point of being sub-sonic.
-They are very bright, and have an oval, spherical, or elongated shape much like a lance or a needle.
-Defy gravity, especially with particle beams and plasma, despite having mass, even if it is very little.
-Their effects vary, from neat burn holes to larger burns, causing the target to glow and disappear, either the flesh or the entire body, and causing non-organic materials to explode.
Now one must wonder, what is the utility of such inefficient, sluggish weapons that are vastly inferior to the capabilities of conventional weapons? Obviously, the answer is very simple; people, especially the writers and effects crew, like their pretty lights and unrealistic effects, and so does the audience. It is an inevitable expectation from the audience that has to be satisfied.
This comes out of the excuse that basically says "its fiction so we can do whatever we want" despite not doing any actual research or looking at the relevant science. If they did, lasers and particle beams would strike instantly, with the former normally being invisible and the latter looking like straight-lined lightning. Plasma would look similar as well, and all of the effects of these weapons would be somewhat gruesome.
-Lasers; if they are continuous, you would get damage much like being sprayed by burning napalm, i.e. blistered, burnt flesh. If it is pulsed correctly, the wound will be like a gunshot wound without a bullet because the the target area is rapidly superheated to the point that it explodes, and if done correctly this digs into the victim.
-Particle Beams; similar effects, and in addition there is radiation damage, which by itself can be fatal, sometimes instantly if it is powerful enough. Depends on the beam type, which if it is an electron type, results in electrocution.
-Plasma; would perform largely as it does in the Halo novels, except as a practical weapon it would be a far denser version of a particle beam, and its effects would be larger scale and severe. Extreme burn damage combined with the kinetic impact of the plasma shot. The beam would look like a bright beam rather than a discreet blob or needle.
Common characteristic: since flesh has a great deal of water in it, they would tend to rapidly and instantly reach their flash point, leading to burn damage and in the right cases explosive effects on flesh. This is shared by all the aforementioned weapon types, most prominently in lasers and probably in plasma.
A widely used trope onto itself, this is a common explanation for otherwise undefined generic energy weapons with standard incompetence and uselessness as their main characteristics. Typically represented as either blobs, circles, or tear drop-shaped glowing masses moving at pathetically slow speeds. The damage they do varies, but is usually limited to a neat and viewer-friendly burn mark.
But why would anyone use a weapon that is utterly useless? Many factors in the real world would make the way these weapons as presented impossible. For starters, plasma is incredibly diffuse, chaotic, and nearly impossible to confine, and when exposed to an atmosphere or non-vacuum environment, typically instantly disperse and lose their original energy.
In order to work properly, it would have to either be very dense, have some ridiculously powerful containment field, have all the particles move in a straight line and at effectively relativistic speeds, or be generated in a manner similar to a what might be involved in Ball Lightning.
Interestingly, a theory about this is available, which I stumbled upon the other day:
On another note, this company even tried to get it used as a weapon, which employed the techniques the articles described to launch a sufficiently stable plasma ring a few feet in diameter and fire it at a target, disabling its electronics.
In any case, how might this be applied to Halo? A few years ago, when an HBO forum goer asked about plasma weapons and if they could be blocked, Frank O'Connor stated that they weren't plasma by a strict definition, but "something arcane and much more destructive." While this is rather vague anda response to a concept that is generally implausible, it definitely provides food for thought.
From what we've seen and read, it is clear that Covenant weaponry is discharging plasma, but the nature of it is still a mystery. The UNSC doesn't fully understand it, and magnetic fields have been described time and again to play an important role. But what role might that be?
Given the shape and characteristics of a typical plasma shot, we know that the stabilizing and containment effect lasts for only a short period of time, so perhaps it is some magnetically-derived synchronization within the plasma itself, or it is put together in a manner that is similar to the Prometheus II idea.
So perhaps it is an exotic application of advanced but known physics that keeps the plasma stable long enough to hit a target. However, another complication of plasma weapons is that they would also run into atmospheric resistance and being robbed of their heat and energy. One possible solution is to have the air blasted either away or heated, and firing the plasma shot right after, so it doesn't so readily disperse.
This could be accomplished by a suitably powerful pulsed laser, and the plasma weapon itself would have a design similar to rocket nozzels, except be mostly magnetic in nature. An example of such nozzels are shown in this link.
Basically, you'd have a weapon with a staged firing operation. First the plasma is generated and heated, formed and then accelerated in a stable fashion, while simultaneously a pulse laser is fired to make an appropriate path. The plasma is shot in a quick, pulsed burst, with the laser fired again to keep the plasma hot as it moves down range.