Helicons are also utilized in the procedure of plasma etching, used in the manufacture of computer microcircuits. A helicon discharge is an excitation of plasma by helicon waves induced through radio frequency heating. The difference between a helicon plasma source and an inductively coupled plasma (ICP) is the presence of a magnetic field directed along the axis of the antenna. The presence of this magnetic field creates a helicon mode of operation with higher ionization efficiency and greater electron density than a typical ICP. The Australian National University, in Canberra, Australia, is currently researching applications for this technology. A commercially developed magnetoplasmadynamic engine called VASIMR also uses helicon discharge for generation of plasma in its engine. Potentially, Helicon Double Layer Thruster plasma based rockets are suitable for interplanetary travel. A simple experiment can be conducted with fairly affordable equipment, and may be found in university-level undergraduate advanced physics laboratory courses. A metal such as 99.999% pure indium is commonly used: it is cooled using liquid helium to reach the conditions of low temperature, while the high magnetic field is accomplished using a superconducting solenoid. Ultimately, the experiment characterizes the resonance frequency and resonance width of the helicon standing waves. It can also be used to measure the magnetoresistance and Hall coefficients of the pure metal.