Simple radio-frequency power source for ion guides and ion traps

A high power oscillator circuit, designed to power radio-frequency (rf) ion guides and traps, is described. The rf circuit is directly coupled to the guide/trap electrodes, and no frequency or impedance matching is required. The design provides precisely adjustable rf amplitudes from ∼50 to 600 V, either under manual or computer control. The operating frequency can be varied from <1 to ∼30 MHz to allow best trapping conditions for different ion mass ranges. Provisions are made for balancing the rf amplitude to compensate for small load asymmetries. The rf can be switched off and on under control of a transistor–transistor logic signal, and the rise and fall time for the rf amplitude can be manually controlled from a few rf cycles to milliseconds. Provisions are made for applying both direct current (dc) difference and dc float potentials to the ion guide. The design is easily constructed from readily available parts.