Influence of magnet arrangement on high-density hydrogen plasma produced by a capacitively coupled magnetized discharge using a hybrid hollow electrode under a lower gas pressure

Generating a high-density capacitively coupled magnetized plasma in hydrogen in the presence of a hollow electrode having a single cylindrical groove with magnets at a frequency of 13.56 MHz and pressures less than 3 Pa for thin film preparation and as negative ion source is a challenge. Here, the influence of the magnet arrangement on the high-density plasma produced by a capacitively coupled magnetized discharge using a hybrid hollow electrode, which consists of a center cylindrical groove and an outer ring-shaped groove, under a lower gas pressure of less than 3 Pa has been investigated. Eight cylindrical Neodymium magnets are arranged outside the center groove and the outer groove, respectively. Two magnet arrangements where opposing magnets have either the same or different polarity are examined. A 2D magnetic field simulation indicates that for the same polarity an electron Hall parameter, which is the product of the angular cyclotron frequency and an electron-neutral collision time, is higher than 60 in the outer groove, for the different polarity it has a null point in the outer groove and is higher than 100 near the wall, whereas in the center groove it has a similar distribution and is higher than 100, for both magnet arrangements. Under a low pressure of 1 Pa, the high-density plasma is produced for both magnet arrangements with a peak plasma density of 2.8 × 10¹⁰ and 6.0 × 10¹⁰ cm^-3 for the same and different polarity, respectively, under the fixed input power of 50 W.