General Omnigenity BCs

[ddudt]

• If OH & OT can't exist at the axis (has to be QS), then we should enforce the target field to have mirror ratio = 0 on axis
• Probably don't need any extra BCs on x_lmn at the axis, because if B(eta)=const it has to be QS regardless of h(eta,alpha)
• But what about as it approaches the axis? The rate of the omnigenity params approaching QS has to not conflict with the rate of the NAE constraints
• Any required BCs on rho dependency are going to be on B_ij (well shape). x_lmn (stretch/shift) probably never needs any BCs?
• Plunk 2019 Section 6.1 seems to prove that OT is not possible on or near the axis. But what about OH?

[dpanici]

Any non-poloidally closed contour must be const. B on-axis

[dpanici]

Self constistncey constraint that adds this when OH or OT is being used (checks helicity to check if is OH or OT), to only enforce that omni field is QS on axis (constant |B|)