To put it in simple terms, a comet's debris trail or dust trail is like a ring of debris that generally follows the entire orbit of the comet, more concentrated close to the comet, more spread out further away, but it can be thought of, for simplicity, as an entire ring of debris, kind of, a miniature asteroid belt with a fixed elliptical path. The picture below isn't perfect, cause it gives the impression that orbits are all the same when there's some spreading out, but it's the gist of it. (Note, the debris field and comet in the picture below isn't Swift-Tuttle/Perseid)
The reason for this is that any debris that's knocked off the comet at a low velocity has pretty much the same orbit as the original comet, and over hundreds or thousands of orbits, it tends to fill up the entire comet's orbit with mostly tiny particles, some larger ones. The debris field or dust trail from the comet generally follows in the comets orbit.
This picture is a bit more accurate as to what the Earth is passing through.
https://lintvwpri.files.wordpress.com/2016/08/perseid_base4.png?w=650&h=366
The more compact the dust trail or debris field, the more meteors, but the smaller the target the Earth has to hit, so odds are greater that the Earth will miss the field entirely. The more spread out, the greater chance the Earth hits the debris field, but more spread out means we get fewer meteors.
Earth's orbit crosses the Perseid (eliptical ring of debris) or Swift-Tuttle's debris field about the same time every year because Earth's and Swift-Tuttle's orbits nearly intersect.
This year, because of the placement of Jupiter, the debris field (which we can kind of think of as a ring), got bent by Jupiter, and Earth is hitting closer to the center of the debris field which means, more meteors. I can't say on which plane the field got bent, cause it depends on it's orbital relation to Jupiter and I couldn't find that, but it was the ring of debris that got bent, so Earth will hit it more directly this year than usual.
Because the ring of debris is pretty much permanent, Jupiter bends the ring every 11 years as it passes closest to it, and occasionally that bend works in earths' favor and gives us more meteors, so its a rare event that might not happen again for 11 years, it might be over 100 years before Jupiter does this for us again.
See article.
Typically Earth just grazes by Swift-Tuttle’s debris field, but our
planet will be even closer to the particle stream this year thanks to
some help from our neighbor Jupiter. The gas giant occasionally gets
close to the comet stream, and its immense gravity pushes the debris
nearer to Earth.
