The Electrostatic Energy Analyzer (ESA) measures the energy-per-charge distribution downstream of an ion thruster, Hall-effect thruster, ion source, or other plasma device.
The ESA is a spherical deflector type analyzer, having two concentric electrodes that curve ions (or electrons) along a curved path to a collector electrode. The current to the collector is measured as a function of either 1) the voltage difference between the segments, or 2) the accelerating or decelerating potential with a fixed voltage difference, yielding the the energy-per-charge distribution. Entrance and exit collimators are used to select a narrow field-of-view.
Segment angle: 120 degrees
Radius of the optical axis: 5 cm
Lead Time: Typically 6 weeks if not in stock.
The "Probe Only" option is the ESA having a 6-pin connector carrying electrode biases and a triaxial connector carrying the collector current.
The "Probe + Feedthrough + Cables" option includes the probe, in-vacuum and air-side teflon-based cables, and double-ended 6-pin and triaxial feedthroughs. By default, each cable is 10 feet (3 meters) long, and the feedthroughs are mounted on KF40 flanges - we will confirm these options prior to assembly.
Accessories: Plasma Controls can provide both in-vacuum and air-side cables at customer-specified lengths, as well as feedthroughs mounted on KF16, KF40, KF50, Conflat CF1.33, CF2.75, CF3.375, NASA 4.5"OD standard, or customer-specified flanges.
The customer will typically need to provide a laboratory power supply (e.g. ~600 V at low current) and a sensitive electrometer/ammeter for measurements. Plasma Controls can provide custom quotes for this equipment and LabView or python-based software.
The information gleaned from the ESA is similar to that from a Retarding Potential Analyzer (RPA). The RPA is physically smaller than the ESA and has fewer parts; however, the ESA trace does not have to be differentiated to obtain the energy distribution function.