KICK, HKICK, VKICK

EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH

Closed Orbit Correctors

Three types of closed orbit correctors are available:

HKICKER, a corrector for the horizontal plane,
VKICKER, a corrector for the vertical plane,
KICKER, a corrector for both planes.

label:   HKICKER, L=real,KICK=real,TILT=real;
label:   VKICKER, L=real,KICK=real,TILT=real;
label:   KICKER,  L=real,HKICK=real,VKICK=real,TILT=real;

The type KICKER should not be used when an orbit corrector kicks only in one plane.

The attributes have the following meaning:

L: The length of the closed orbit corrector (default: 0 m).
KICK: The kick angle for either horizontal or vertical correctors. (default: 0 rad).
HKICK: The horizontal kick angle for a corrector in both planes (default: 0 rad).
VKICK: The vertical kick angle for a corrector in both planes (default: 0 rad).
TILT: The roll angle about the longitudinal axis (default: 0 rad). A positive angle represents a clockwise rotation of the kicker.

A positive kick increases p_x or p_y respectively. This means that a positive horizontal kick bends to the left, i.e. to positive x which is opposite of what is true for bends.
It should be noted that the kick values assigned to an orbit corrector like above are not overwritten by an orbit correction using the CORRECT command. Instead the kicks computed by an orbit correction and the assigned values are added when the correctors are used.

Examples:

HK1:   HKICKER, KICK=0.001;
VK3:   VKICKER, KICK=0.0005;
VK4:   VKICKER, KICK:=AVK4;
KHV1:  KICKER,  HKICK=0.001,VKICK=0.0005;
KHV2:  KICKER,  HKICK:=AKHV2H,VKICK:=AKHV2V;

The assignment in the form of a deferred expression has the advantage that the values can be assigned and/or modified at any time (and matched !).
The straight reference system for an orbit corrector is a Cartesian coordinate system.

Please note that there is a new feature introduced by Stefan Sorge from GSI. Here his decription:

The elements KICKER, HKICKER, and VKICKER can also be used as an exciter providing a sinusoidal momentum kick. The usage in this case is

xykick: KICKER, SINKICK=integer, SINPEAK=real, SINTUNE=real, SINPHASE=real;

xkick : HKICKER, SINKICK=integer, SINPEAK=real, SINTUNE=real, SINPHASE=real;

ykick : VKICKER, SINKICK=integer, SINPEAK=real, SINTUNE=real, SINPHASE=real;

where a sinusoidal momentum kick dpz as a function of the revolution number n given by

dpz(n)=SINPEAK * sin(2*PI*SINTUNE*n + SINPHASE), pz=px,py

is provided. So, the variables are

SINKICK - integer, must be set to 1 to switch on the sinusoidal signal, default: 0.

SINPEAK - amplitude of the bending angle (rad), default: 0 rad.

SINTUNE - frequency of the signal times the revolution frequency. Hence, the phase per revolution is 2*PI*SINTUNE, default: 0.

SINPHASE - initial phase, default: 0 rad.

KICKER generates a kick in horizontal and a kick vertical direction, where both are synchron, HKICKER generates a horizontal kick, and VKICKER generates a vertical kick.

The momentum kick of a kicker has only a single frequency. An element having a finite bandwidth can approximately created by defining thin kickers with all amplitudes SINPEAK, frequencies SINTUNE, and initial phases SINPHASE desired and putting them at the same position s in the accelerator.

From S.Sorge@gsi.de

hansg, frs, August 28, 2003