A better method for Stark deceleration uses a new high-voltage amplifier

Using Stark deceleration to slow down and cool molecules for study is a highly useful, but technically challenging approach. Two main techniques can be used: pulsed-pin Stark deceleration (PPSD) and traveling-wave Stark deceleration (TWSD). The more traditional PPSD option is easier to access with readily available high-voltage switches to control electric fields, but also tends to be less efficient with a somewhat higher loss rate than the new TWSD method.

However, while the newer TWSD technique promises far greater efficiency, its chirped sinusoidal voltages demand high-voltage amplifiers with complex and demanding specifications. Shyur et al. developed a new linear high-voltage amplifier capable of meeting the bandwidth, current and voltage requirements needed for practical TWSD.

The design is centered on an all n-channel FET-based push-pull design, since this was considered the simplest method to undertake series FET stacking in an amplifier capable of handling high voltages. Consisting of two banks, each with one leader and nine follower stages, the authors tested the amplifier with various loads and frequencies using a high-voltage capacitor to simulate a Stark decelerator apparatus. It demonstrated output voltages of up to ±10 killivolts, instantaneous currents up to 1.5 amps, and a frequency range from 30 killohertz down to DC.

Such peak voltages will permit deceleration of small polar molecules as the bandwidth allows deceleration to rest of a molecular beam. These capabilities, the authors note, exceed those of any currently available commercial high-voltage amplifier, thus greatly enhancing the prospects for more accessible TWSD experimentation.

Source: “A high-voltage amplifier for traveling-wave Stark deceleration,” by Yomay Shyur, N. J. Fitch, Jason A. Bossert, Terry Brown, and H. J. Lewandowski, Review of Scientific Instruments (2018). The article can be accessed at https://doi.org/10.1063/1.5040267 .