Pulse modulation radio-frequency（RF） has lots of adjustable parameters（modulation frequency

duty cycle

input power and so on）

which can regulate plasma parameters at a large scope. Compared to AC or DC discharge

RF discharge has its distinctive features. We experimentally investigated the electrical properties of Ar/CO

2

discharge driven by a 13.56 MHz RF power system at atmospheric pressure

and investigated the influences of modulation parameters and gas composition on the discharge initial voltage

α–γ pattern transformation voltage

and the volt-ampere（U-I） curve. The experimental results show that change of modulation parameters and gas composition can affect the breakdown and U-I characteristics to a large extent. The decrease of duty ratio can improv

e the breakdown voltage

mode transformation voltage and operating range of α mode

but the decrease of CO

2

content can bring the opposite effect which the modulation frequency shows a non-monotonic effect on the above characteristics. This study provides more options for RF discharge plasma technology to improve CO

2

utilization efficiency.