Halfa

 alfa is the term for humans infused with ghost powers, via ecto-energy.

Creation
Like normal ghosts Halfi are humans but rather than dying are infected or infused with ecto energy, some like Vlad, and Danny are infused with excess energy from being caught in the cross demensional fabric of the ghost zone; others like Vedgied Sam, are connected to a powerful ghost, and get their powers through a fusion of ecto-energy that has yet to be explained; Danielle on the other hand was a clone, and thus a mixture of human-ghost DNA.

Powers & Weakness
Halfi have all the powers and advantages of both humans and ghosts, however while in ghost form they are seceptible to ghost weaknesses like blood-blossoms, also they can be weakened by anti-ecto energy even while in their human forms. Their is also a limit to how much ecto-energy they can produce, and when they run out they are gravely weakened, and virtually defenseless.

Ecto-D Suits
The Ecto-D suits are suits specially made by Jack, via a morph-DNA sample of his son`s morphing. The Ecto-D suits have a limited supply of Ecto Energy for usage of standard ghost-powers, such as levitation, it also has a built in ghost sense of a red warning flash. Valerie Gray modified her battle suit, into an ecto-D battle suit with a DNA morph of Danielle, and the left behind work of Vlad Masters.

Vlad Plasmius
Vlad Plasmius was infected with Ghost DNA via the proto-protal exploding, he was not infected with as much ecto-energy so he cannot produce as much as Danny Phantom.

Danny Phantom
Danny Phantom was the second Halfa born from his father`s calculations on the subject of Ectology. He actidentally activated the ghost-zone portal from inside was the caught in the dimensional rip, (noteworthy is that this rip was more stable and didn`t have the ecto-ancé side effect) thus giving him ghost powers, and two that Vlad seems to lack, Cryokenesis, and the Ghostly Wail.

Dani Phantom
Trying to create his perfect clone Vlad Plasmius tried to create a son, but some of his DNA was caught in one of the clones by acident, thus causing an unexplained effect of Dani being a girl ghost, with a human self, stirring from the Fenton side, of Danny Phantom.

Sam
Sam is a very Unique Halfa as she was actually fused with ghost DNA of Undergrowth, thus she became the Halfa Vedgied Sam through a more stable way than any other halfa shown. When Undergrowth was defeated, Sam reverted back and it was confirmed by Mangaka Hans Growl that Sam is still a Halfa and simple has yet to awaken it.

Hospitalized Halfi, via Spectra-Virus
Spectra infected the students at Casper High with her ghost bugs with only Tucker and Danny unneffected, she used this as an oppertunity to extract the best of every body, the Ghost Powers are a side-effect, but Growl confirmed that it will play an important part for Sam later in the series.

Phantomized Tucker
Like Sam, Tucker was fused with Ecot-Energy during the cartoon, however his was via Desere`s powers, and had to be seperated from his ghost powers, unlike sam his connection to the powerful ghost he was connected to was severed, confirmed by Growl.

Ectology
Main Artical: Ectology

Ectology is the study of ghosts, and is the main foundation for Halfa research.

Trivia

 * Sam is the only Halfa from the Hospitalized Casper High that experienced ghost powers a second time in the TV series. Growl confirmed that she will regain her powers later in the Manga.


 * Tucker is the only member of Casper High not to experience the Halfa-bug he was however he was effected wtih excess Ghost-DNA by a wish, he was the most unstable of the Halfi.


 * Ecto-D suits use DNA-less Morphing samples to allow the morphing on Dash, Valerie, and Kwan.


 * The Hospitalized Students of Casper High still have Ghost powers from excess DNA but simply cannot acess then do to poor concentration of ecto-energy.