diff --git a/mbtrack2/tracking/FeedBack.py b/mbtrack2/tracking/FeedBack.py
new file mode 100644
index 0000000000000000000000000000000000000000..14a41e0ed5fbb215ab492e80c9754d2f6e72e4e8
--- /dev/null
+++ b/mbtrack2/tracking/FeedBack.py
@@ -0,0 +1,170 @@
+# -*- coding: utf-8 -*-
+"""
+Created on Tue May 3 09:36:24 2022
+
+@author: sauret
+"""
+from mbtrack2.tracking.element import Element
+import numpy as np
+
+class FeedBackTransverse(Element) :
+ """
+ Transverse feedback system to counter transverse instabilities.
+
+ Parameters
+ ----------
+ ring : Synchrotron object
+ turn_delay : int, optional
+ Number of turn delay before applying kick.
+ tap_number : int, optional
+ Number of tap for the FIR filters.
+ ampl : float, optional
+ Gain of the FIR filters.
+ phase : float, optional
+ Phase of the FIR filters in deg.
+
+ Attributes
+ ----------
+ x_pos : array
+ Retrieves and stores the position of the bunch, measured by the BPM,
+ in horizontal plane.
+ y_pos : array
+ Retrieves and stores the position of the bunch, measured by the BPM,
+ in vertical plane.
+ kick_x : array
+ Stores the numerical values of the kicks for the horizontal plane.
+ kick_y : array
+ Stores the numerical values of the kicks for the vertical plane.
+ coef_x : array
+ Stores the coefficients of the FIR filter for the horizontal plane.
+ coef_y : array
+ Stores the coefficients of the FIR filter for the vertical plane.
+ """
+
+ def __init__(self, ring, turn_delay=1, tap_number=5, ampl =1e-1, phase = -90):
+
+ self.ring = ring
+ self.turn_delay = turn_delay
+ self.tap_number = tap_number
+ self.ampl = ampl
+ self.phase = phase
+ self.x_pos = np.zeros((self.tap_number,))
+ self.y_pos = np.zeros((self.tap_number,))
+ self.kick_x = np.zeros((self.turn_delay+1,))
+ self.kick_y = np.zeros((self.turn_delay+1,))
+ self.coef_x = self.get_fir_x()
+ self.coef_y = self.get_fir_y()
+
+ def get_fir_x(self):
+ """
+ Compute the FIR coefficients for the horizontal plane.
+
+ Returns
+ -------
+ coef_x : array
+ Array containing the FIR coefficients for the horizontal plane.
+ """
+ phi_x = 2*np.pi*self.ring.tune[0]
+ zeta = (self.phase*2*np.pi)/360
+ coef_x = np.zeros((self.tap_number,))
+
+ it = np.zeros((self.tap_number,))
+ for k in range(self.tap_number):
+ it[k] = (-k - self.turn_delay)
+
+ cs_x = np.zeros((self.tap_number,))
+ sn_x = np.zeros((self.tap_number,))
+ for i in range(self.tap_number):
+ cs_x[i] = (np.cos(phi_x*it[i]))
+ sn_x[i] = (np.sin(phi_x*it[i]))
+
+ CC_x = np.zeros((5, self.tap_number))
+ for j in range(self.tap_number):
+ CC_x[0][j] = 1
+ CC_x[1][j] = cs_x[j]
+ CC_x[2][j] = sn_x[j]
+ CC_x[3][j] = it[j]*sn_x[j]
+ CC_x[4][j] = it[j]*cs_x[j]
+
+ TCC_x = np.transpose(CC_x)
+ W_x = np.linalg.inv(CC_x.dot(TCC_x))
+ D_x = W_x.dot(CC_x)
+
+ for n in range(self.tap_number):
+ a_x = self.ampl*(D_x[1][n]*np.cos(zeta) + D_x[2][n])
+ coef_x[n] = (a_x)
+
+ return coef_x
+
+ def get_fir_y(self):
+ """
+ Compute the FIR coefficients for the vertical plane.
+
+ Returns
+ -------
+ coef_y : array
+ Array containing the FIR coefficients for the vertical plane.
+ """
+ phi_y = 2*np.pi*self.ring.tune[1]
+ zeta = (self.phase*2*np.pi)/360
+ coef_y = np.zeros((self.tap_number,))
+
+ it = np.zeros((self.tap_number,))
+ for k in range(0,self.tap_number):
+ it[k] = (-k - self.turn_delay)
+
+ cs_y = np.zeros((self.tap_number,))
+ sn_y = np.zeros((self.tap_number,))
+ for i in range(self.tap_number):
+ cs_y[i] = (np.cos(phi_y*it[i]))
+ sn_y[i] = (np.sin(phi_y*it[i]))
+
+ CC_y = np.zeros((5, self.tap_number))
+ for j in range(self.tap_number):
+ CC_y[0][j] = 1
+ CC_y[1][j] = cs_y[j]
+ CC_y[2][j] = sn_y[j]
+ CC_y[3][j] = it[j]*sn_y[j]
+ CC_y[4][j] = it[j]*cs_y[j]
+
+ TCC_y = np.transpose(CC_y)
+ W_y = np.linalg.inv(CC_y.dot(TCC_y))
+ D_y = W_y.dot(CC_y)
+
+ for n in range(self.tap_number):
+ a_y = self.ampl*(D_y[1][n]*np.cos(zeta) + D_y[2][n]*np.sin(zeta))
+ coef_y[n] = (a_y)
+
+ return coef_y
+
+ @Element.parallel
+ def track(self, bunch):
+ """
+ Tracking method for the feedback system
+ No bunch to bunch interaction, so written for Bunch object and
+ @Element.parallel is used to handle Beam object.
+
+ Parameters
+ ----------
+ bunch : Bunch or Beam object
+ """
+ self.x_pos[0] = bunch.mean[0]
+ self.y_pos[0] = bunch.mean[2]
+
+ x_kick = 0
+ y_kick = 0
+
+ for k in range(self.tap_number):
+
+ x_kick += self.coef_x[k]*self.x_pos[k]
+ y_kick += self.coef_y[k]*self.y_pos[k]
+
+ self.kick_x[-1] = x_kick
+ self.kick_y[-1] = y_kick
+
+ bunch["xp"] -= self.kick_x[0]
+ bunch["yp"] -= self.kick_y[0]
+ self.x_pos = np.roll(self.x_pos,1)
+ self.y_pos = np.roll(self.y_pos,1)
+ self.kick_x = np.roll(self.kick_x, -1)
+ self.kick_y = np.roll(self.kick_y, -1)
\ No newline at end of file
diff --git a/mbtrack2/tracking/monitors/plotting.py b/mbtrack2/tracking/monitors/plotting.py
index e41904e462e8ccaa4b2ec5c8f7e1b5402c694e86..d7ca1cee3bdb8f64ccc001df59276aeacebcf4f7 100644
--- a/mbtrack2/tracking/monitors/plotting.py
+++ b/mbtrack2/tracking/monitors/plotting.py
@@ -358,7 +358,7 @@ def plot_phasespacedata(filename, bunch_number, x_var, y_var, turn,
"$\\delta$"]
# find the index of "turn" in time array
- turn_index = np.where(file["PhaseSpaceData_0"]["time"][:]==turn)
+ turn_index = np.where(file[group]["time"][:]==turn)
if len(turn_index[0]) == 0:
raise ValueError("Turn {0} is not found. Enter turn from {1}.".