  A novel radio-frequency antenna consisting of isolated solenoids is reported
to generate plasma for pressure up to thousands of pascals. The underlying
mechanism involves capacitive coupling, inductive coupling and axial
confinement from magnetic mirrors. It can ionize the air reliably with pressure
up to $2500$~Pa for the $1$~kW-$13.56$~MHz power supply employed, and maintain
the discharge steadily from tens of minutes to hours. This ionization method is
particularly useful for plasma propulsion in near space and other
low-temperature plasma applications where sub-atmospheric pressure is required.
