Quadrupoles

label:QUADRUPOLE,TYPE=string,APERTURE=real-vector,L=real,K1=real,K1S=real;

A QUADRUPOLE has three real attributes:

L

The quadrupole length (default: 0 m). A thin quadrupole is defined by setting the length to zero.

K1

The normal quadrupole component $K_1=\frac{1}{B \rho}\frac{\partial B_y}{\partial x}$. The default is $0 \mathrm{m}^{-2}$. The component is positive, if $B_y$ is positive on the positive $x$-axis. This implies horizontal focusing of positively charged particles which travel in positive $s$ direction.

K1S

The skew quadrupole component $K_{1s}=\frac{1}{B \rho}\frac{\partial B_x}{\partial x}$. The default is $0 \mathrm{m}^{-2}$. The component is negative, if $B_x$ is positive on the positive $x$-axis.

Example:

QF:QUADRUPOLE,L=1.5,K1=0.001;

The reference system for a quadrupole is a Cartesian coordinate system.