MCP observations of 250 eV proton beam as a function of input current. (a)–(g) MCP observations at 0.16, 0.22, 0.32, 0.42, 0.52, 0.62, and 0.7 A input current, respectively. (h) Total count rate on the MCP as a function of input current.
Measurements of lighter, low-energy charged particles in a laboratory beamline are complicated due to the influence of Earth’s magnetic field. Rather than nulling out the Earth’s magnetic field over the entire facility, we present a new way to correct particle trajectories using much more spatially limited Helmholtz coils. This approach is versatile and easy to incorporate in a wide range of facilities, including the existing ones, enabling measurements of low-energy charged particles in a laboratory beamline.