Stanford CHENG Gun

cheng gun

The Stanford CHENG Gun (SCG) is a pulsed, direct electrode plasma source that produces a high velocity, high energy density plasma jet in vacuum. The physical mechanism of acceleration to speeds of over 100 km/s is known to be related to the phenomenon of plasma deflagration, and is also an area of active research. The facility is designed to experimentally reproduce extreme plasma environments such as those found near the walls in tokamak fusion reactor disruption events, and to use these conditions to study plasma-material interactions. The ultimate goal of the project is to provide strategies for understanding and solving the so-called “first wall problem” of safe, reliable fusion power production in a terrestrial reactor.

Stanford Mini Heated Helicon


The Mini Heated Helicon (MHH) project is a joint effort between the Cappelli group and Professor Rivas’ group in the Electrical Engineering Department at Stanford University. We are designing and testing a 50 W helicon discharge for use in microsat propulsion, powered by Professor Rivas’ miniature 40 MHz RF generators.

Plasma Thrusters and Diagnostics


The SPPL large vacuum facility enables ground testing of various plasma devices used for space propulsion and ion acceleration at very low pressures (10^{-6} torr). The Z-70 Hall Thruster, Stanford Cylindrical Cusped Field Thruster (CCFT), and MIT Diverging Cusped Field Thruster (DCFT) have all been investigated with probes and laser diagnostics seeking to understand the physical mechanisms underlying propellant ionization, electron transport, and ion acceleration. New developments in laser induced fluorescence (LIF) spectroscopy allow us to measure spatially and time-resolved ion velocity distribution functions in the plasma, synchronizing with periodic or quasi-periodic kHz oscillations.