چكيده به لاتين
Transcranial brain magnetic stimulation (TMS) is one of the non-destructive methods of stimulation, which has received a lot of attention from research and academic centers in the past years. In this thesis, after examining the factors affecting non-destructive transcranial magnetic stimulation of the brain, an attempt was made to propose an operational method based on solving Maxwell's equations and solving the wave equation, in order to improve the depth of stimulation and the concentration of the field created inside the object in question (here, the head is human) has become At first, by examining the specifications and concepts used in the TMS device, we will draw its circuit model and build a laboratory sample that can be used in the frequency range up to 4 Hz, and present the test reports of the field shape and its outputs. In order to improve the stimulation depth, we use the solution of using a structure with adjustable physical parameters, and for that we solve the problem in two dimensions and with a simplified problem, which is a structure consisting of water, muscle and bone, and we calculate the electromagnetic scattering equations for this structure so that we can We get the fields inside the object and finally the shape of the object by calculation method and finally we introduce a new equation to obtain the physical characteristics of the object from the landing field and the total field inside the object. Then by adding an adjustable structure consisting of the physical characteristics of the material next to the object and using the genetic algorithm, we will try to find the physical characteristics of the added structure to create a desired electric field in a part of the object. This technique is used for the simplified head model that consists It is made of three layers of skin, bone and brain, and we use an infinite current wire at low frequency and with the radiation field. In the next step, another solution is to place an arbitrary material with high relative permeability, which we call magnetic material, next to the human head and in the environment of simulating and changing the structural shape of this material and examining different locations around the head, we find the distribution The field inside the head and the intensity of the induced field are different and in the center of the head we see an improvement in the penetration depth of the field.
