重離子放射治療癌症是目前最先進有效的方法，從設備到治療過程相當複雜，其中使用的離子加速設備有離子源、直線加速器、同步加速器，在治療病人的過程中需要使用高強度離子束轟擊腫瘤，然而為了產生高強度的離子束，本文針對電子迴旋共振離子源放電實際物理情形，以粒子模擬法與蒙地卡羅方法模擬粒子動力學情形，接著利用有限差分時域法計算不同時間格點上的電場與磁場。在本系統中分別進行腔體溫度、氣體溫度及氣體流率參數最佳化模擬，將離子束電流強度以及離子數達到最佳值。主要是當腔體溫度、氣體溫度與氣體流率增加都會使腔體內氣壓增高，使離子密度上升，當腔體內氣壓過高時，導致離子密度與離子束電流強度降低。

SUMMARY
One of the most important method for cancer treatment is heavy ion radiotherapy nowadays. However the construction of this method is complicated which includes ion source, linear accelerators and synchrotron. High intensity stable ion beams for the elimination of tumor in treating patients. In order to produce high intensity ion beam, we emphasis on the electric dynamic behavior in electron cyclotron resonance (ECR). In this thesis, Particle-In-Cell and Monte Carlo methods are applied to discuss particle dynamic phenomena, and then, the electric and magnetic field were evaluated by Finite-Difference Time-Domain. In the present system for the chamber temperature, gas temperature and gas flow rate simulation parameters were optimized, and the intensity of the ion beam current reaches the optimum value. Mainly because of that when the temperature of the chamber, the gas temperature and gas flow rate will cause the body to increase the air pressure chamber increased. The ion density increased the air pressure chamber when the body is too high, causing the ion beam current density and strength.

INTRODUCTION
Heavy ion therapy device is composed of Ion Source, Linear Accelerator, Synchrotron, Dose Delivery System, and Treatment Platform. Among them, the Ion Source produces an ion beam that charges state and beam intensity, which is needed to achieve a certain level in order to develop the potential of cyclotron and synchrotron. Therefore, the development of heavy ion source has become the most important part of the study. The initial Ion Source can’t be operated continuously for a long time to reduce the generation of multi-charged ions, dramatically reducing the cyclotron performance. In 1980, the electron cyclotron resonance ion source is applied in a cyclotron for the very first time. The cyclotron to the dramatically improve the performance. Due to the electron cyclotron resonance ion source improves the state of charge of the ion beam intensity and ion beam current, also, could be operated continuously for a long time. Electron Cyclotron Resonance ion source involves a lot of basic science, such as plasma physics, microwave theory, and atomic physics. Also, the magnetic field is applied to the complex technology, vacuum technology, permanent magnet technology, and microwave technology.

MATERIALS AND METHODS
Although the electron cyclotron resonance ion source has been widely used, but the actual physical behavior of the cavity is not clear. To more clearly understand the actual
physical situation, this paper is according to the Particle-in-cell, PIC simulation method and the Monte Carlo simulating the behavior of an electron cyclotron resonance plasma chamber, followed by the usage of FDTD method (Finite-Difference Time-Domain) and the calculation of electric and magnetic fields at different time points on the grid. The temperature of the chamber, respectively, the gas temperature and gas flow rate parameter optimization simulation, the strength and the ion beam current reaches the optimum value.This article is about the use of VSimComposer in the simulation of ECR plasma ion source by using PIC (Particle In Cell) simulation method plasma simulation method, which is based on the concept of macro particle as a bunch of particles moving clouds. Moreover, it avoids Debye length and divergence effects Coulomb force and meet the plasma characteristics, and can reduce software computing resources.PIC method is based on the usage of the macro particle moving on a grid, and weighting way to allocate macro amount of charge and the weight of the particles to other grids. Therefore, the more weighting distribution, the higher accuracy will be receive, but relatively more time consuming in the calculation. The solving aspects of the use of FDTD (Finite-Difference Time-Domain) method is to use the Maxwell equations rewritten as a differential equation. Using the Yee grid cutting mode discrete electromagnetic field, and the electromagnetic field partial differential equations and boundary conditions discrete differential treatment, finally, the electric and magnetic fields in a time step iteration, by calculating electromagnetic field changes over time in space. In this paper, using the discharge behavior within VSim ECR ion source plasma simulation. Considering the elastic electron, neutral gas excitation, ionization collisions, elastic, charge exchange of ions and neutral gas collisions.

RESULTS AND DISCUSSION
Regional ECR discharge behavior is the axis of symmetry, the three-dimensional geometry of the simplified two-dimensional, and thus accelerate the computation process. The simulation time step of s, total simulation time is 5ns, microwave frequency of 2.45 GHz, ECR ion source chamber length is 0.18m, radius of 0.02m, the cavity voltage is 25V, the gas flow rate is 4.5sccm, gas temperature is 400K, the temperature of the chamber is 300K, six permanent magnets remanence is 1.42T, and the coercive force is -1114000A / m. Working gas is carbon dioxide, respectively changes the chamber temperature, the gas temperature, and the gas flow rate of the ion beam current strength quantitative analysis. The study has found an extension of the cavity temperature increase the number of ions, but then continues to rise the temperature of the chamber is decreased the number of ions.
Therefore, a given microwave power can be seen, and there is a cavity temperature optimum value. Obviously, the other fixed parameters of the gas temperature and gas flow rate to be modified, which has the same phenomenon as well; mainly because it is under high vacuum. The neutral particles and the average electron collision frequency increases with the neutral gas density has increased. Along with the increasing collision frequency of neutral particles, and the degree of the ionization, electrons and ion density also increases. However, the temperature of the chamber, the gas temperature and gas flow rate will cause the cavity to increase the air pressure when the air pressure continues to increase in the cavity large. It makes the electron mean free path becomes
shorter, so that electrons can’t effectively absorb microwave energy. Resulting in reduced efficiency of the electron gas is ionized, and the collision of charged particles in the cavity increases the probability of a composite. Due to the plasma density decreases, the impact of the ion beam current intensity.

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