A new Corona treater 101 posting does a nice job of explaining that there are differences between the effectiveness of tretament created by each corona treater configuration.

Each Corona Treater has its own unique characteristics

The process of generating corona is essentially the same for all corona treaters. Corona is ionized air created by discharging high frequency high voltage energy across a metal or insulated electrode. This electrode is positioned over a grounded roll, and the space between the electrode and the roll is called the air gap. This is where corona is created and substrates are passed through this gap to receive corona treatment.

The variables of a corona treater are the power supply, electrode type and ground roll type. Traditional metal electrode systems with covered rolls are used extensively in film extrusion applications. High speed photography reveals that these corona systems produce corona with high filamentary discharges. In addition, damage to these types of ground roll coverings can result in inconsistent treatment and eventual roll covering failure.

Meanwhile systems that use ceramic electrodes have the options of using a bare or coated roll. Bare rolls eliminate the possibility of roll covering failure. Many companies will offer a ceramic covered groundroll to complement a ceramic electrode system. However some corona treater designs go a step further with a proprietary roll covering that offers a number of application benefits including insurance against backside treatment and pinholing. High speed photography of the corona generated by these systems depict a more homegenous corona than their either their bare roll or metal electrode counterparts.

The result is a more universal corona discharge which leads to more consistent treatment across a variety of application requirements.