TJ-II:Sectors
The vacuum vessel is subdivided into four (4) sectors or quadrants, corresponding to the 4-fold symmetry of the machine (each sector being essentially identical). The enumeration of the sectors or quadrants (A through D) is shown in the top view of the machine. Each sector is subdivided into eight segments. Each segment has two or three viewports, labelled 'TOP', 'BOTTOM', or 'SIDE'.
The toroidal angle φ is defined as zero between segment D8 and A1, and increases in the counterclockwise direction. North is up, corresponding to φ = 90º.
The location of diagnostics and other devices is given here: TJ-II:Ports
