pod = {
const pod = d3ForcePod()(domEl)
.nodeColor(({ pole }) => COLORS[pole > 0 ? 'positive' : 'negative']);
pod.addForce(d3.forceBounce()
.radius(d => d.r)
.elasticity(0)
);
pod.addForce(d3.forceMagnetic()
.charge(node => node.r*node.r*node.pole*(node.pole>0 ? PROTON_ELECTRON_CHARGE_RATIO : 1))
.strength(ACCELERATION_K)
.polarity((q1,q2) => q1*q2 < 0)
);
return pod;
}