simulations.objects
Class CurrentRing

java.lang.Object
  simulations.objects.BaseObject
      simulations.objects.CurrentRing

public class CurrentRing

extends BaseObject

A ring carrying current. CurrentRing is an EMSource object that computes the electric and magnetic field of a moving circular ring of current. The adjustable parameters are the position, orientation, radius, and velocity of the ring, the current and its time rate of change. To compute the fields, elliptic integrals must be performed, and so using a CurrentRing will slow down computations.

Documentation for the expressions used herein in calculating the magnetic field can be found in the TEAL_Physics_Math document (see Section 3.2.2). This link will work if you have installed the SundquistDLIC code base and documentation as instructed.

Version:

1.0

Author:

Andreas Sundquist

Field Summary

Vec3	c center of the ring
Vec3	d unit vector along the direction of the rings axis, defines the direction of positive current
double	dIdt time rate of change of current
double	I current in ring (positive current is right handed with respect to the axis of the ring)
private Vec3	LastB the last calculated B field value, stored to avoid unnecessary calculations
private Vec3	LastE the last calculated E field value, stored to avoid unnecessary calculations
private Vec3	LastX the last calculated location, stored to avoid unnecessary calculations
Vec3	omega the angular velocity vector of the ring, omega cross r from center gives the angular speed
Vec3	p the observer"s location where we are going to calculate the fields
double	R R = radius of the ring
Vec3	v the velocity of the ring

Constructor Summary

CurrentRing(Vec3 p, Vec3 d, double R, double I)
Constructs a new Current ring.

CurrentRing(Vec3 p, Vec3 d, double R, double I, double dIdt)
Constructs a new Current ring.

CurrentRing(Vec3 p, Vec3 d, double R, double I, Vec3 v)
Constructs a new Current ring.

CurrentRing(Vec3 p, Vec3 d, double R, double I, Vec3 v, Vec3 omega)
Constructs a new Current ring.

Method Summary

Vec3	Bfield(Vec3 x, Vec3 B) Sets "B" to the value of the magnetic field at "x".
private void	CalculateFields(Vec3 x) Computes both the electric and magnetic fields at the observer"s position.
Vec3	Efield(Vec3 x, Vec3 E) Sets "E" to the value of the electric field at "x".
void	Evolve(double dt) A very simple evolution of the CurrnetRing by amount of time "dt".

Methods inherited from class simulations.objects.BaseObject

Bfield, Efield, Pfield, Pfield

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

I

public double I

current in ring (positive current is right handed with respect to the axis of the ring)

dIdt

public double dIdt

time rate of change of current

R

public double R

R = radius of the ring

p

public Vec3 p

the observer"s location where we are going to calculate the fields

c

public Vec3 c

center of the ring

d

public Vec3 d

unit vector along the direction of the rings axis, defines the direction of positive current

v

public Vec3 v

the velocity of the ring

omega

public Vec3 omega

the angular velocity vector of the ring, omega cross r from center gives the angular speed

LastX

private Vec3 LastX

the last calculated location, stored to avoid unnecessary calculations

LastB

private Vec3 LastB

the last calculated B field value, stored to avoid unnecessary calculations

LastE

private Vec3 LastE

the last calculated E field value, stored to avoid unnecessary calculations

Constructor Detail

CurrentRing

public CurrentRing(Vec3 p,
                   Vec3 d,
                   double R,
                   double I)

Constructs a new Current ring. The velocity and the angular velocity and // * the rate of current change are initialized to zero.

Parameters:

p - the position of the center of the ring

d - the axis of the ring

R - the radius of the ring

I - the current in the ring

CurrentRing

public CurrentRing(Vec3 p,
                   Vec3 d,
                   double R,
                   double I,
                   Vec3 v)

Constructs a new Current ring. The angular velocity and the rate of current change are initialized to zero.

Parameters:

p - the position of the center of the ring

d - the axis of the ring

R - the radius of the ring

I - the current in the ring *

v - the velocity of the ring

CurrentRing

public CurrentRing(Vec3 p,
                   Vec3 d,
                   double R,
                   double I,
                   double dIdt)

Constructs a new Current ring. The angular velocity is initialized to zero, as is the speed, but we allow a time rate of change dIdt.

Parameters:

p - the position of the center of the ring

d - the axis of the ring

R - the radius of the ring

I - the current in the ring *

dIdt - the time rate of change of current in the ring

CurrentRing

public CurrentRing(Vec3 p,
                   Vec3 d,
                   double R,
                   double I,
                   Vec3 v,
                   Vec3 omega)

Constructs a new Current ring. The rate of current change is initialized to zero.

Parameters:

p - the position of the center of the ring

d - the axis of the ring

R - the radius of the ring

I - the current in the ring *

v - the velocity of the ring

omega - the angular velocity of the ring

Method Detail

Evolve

public void Evolve(double dt)

A very simple evolution of the CurrnetRing by amount of time "dt". For simplicity, it assumes zero second-order rate of changes and therefore uses simple Euler integration. This method should be overridden or replaced in more complicated situations.

Overrides:

Evolve in class BaseObject

Parameters:

dt - the time step

CalculateFields

private void CalculateFields(Vec3 x)

Computes both the electric and magnetic fields at the observer"s position. This method is used by both Efield() and Bfield().

Parameters:

x - the position of the observer

Efield

public Vec3 Efield(Vec3 x,
                   Vec3 E)

Sets "E" to the value of the electric field at "x". "x" is not modified. Returns: resulting "E". This uses the CalculateFields method.

Specified by:

Efield in class BaseObject

Parameters:

x - the position of the observer

E - the electric field at the observer (calculated)

Returns:

E the electric field at the observer

Bfield

public Vec3 Bfield(Vec3 x,
                   Vec3 B)

Sets "B" to the value of the magnetic field at "x". "x" is not modified. Returns: resulting "B" * This uses the CalculateFields method.

Specified by:

Bfield in class BaseObject

Parameters:

x - the position of the observer

B - the magnetic field at the observer (calculated)

Returns:

B the magnetic field at the observer