Overview of experimental research in WHAM

WHAM is an axisymmetric mirror now in its second year of operation. Through three experimental campaigns, it has established a wide operational parameter range. The ECH and fuel injection systems reliably produce plasmas with line‐average density spanning from below 10¹⁸ m⁻³ to above 10²⁰ m⁻³, moving from gas‐dynamic (highly collisional) to collisionless pitch‐angle scattering regimes. Typical experiments employ limiter/end‐ring biasing and neutral‐beam injection to sustain a sloshing‐ion plasma. A novel equilibrium reconstruction technique, maturing diagnostic suite, and power‐balance analyses document the highest‐performance shots. Progress toward reduced radiated‐power loss (via optimized plasma‐facing materials) and minimized charge‐exchange losses (through conditioning, baking, and enhanced titanium gettering) promise a path to > keV ion plasmas. MHD stability has been explored over a range of mirror ratios, and first experimental results from a fast‐wave ion‐cyclotron heating system are anticipated.