本文選題：霍爾推進(jìn)器 + 低頻振蕩��； 參考：《哈爾濱工業(yè)大學(xué)》2015年碩士論文

【摘要】：霍爾推進(jìn)器(Hall Thruster)是一種利用正交電磁場作用來實現(xiàn)工質(zhì)原子電離以及粒子加速的裝置,由于具有效率和比沖較高,壽命較長的特點,近年來在深空探測和微小衛(wèi)星姿態(tài)控制等領(lǐng)域獲得了廣泛的應(yīng)用。但是,在航天器任務(wù)向多元化發(fā)展的大背景下,人們對于霍爾推進(jìn)器的工作壽命和工作狀態(tài)的穩(wěn)定性要求也越來越高。實驗證明,預(yù)電離可以對放電腔內(nèi)的物理過程以及穩(wěn)態(tài)下的物理參數(shù)產(chǎn)生影響,但是具體的影響過程以及預(yù)電離率的確定還沒有人做過系統(tǒng)分析,本文即針對預(yù)電離對象對低頻振蕩以及緩沖腔的壁面腐蝕狀況展開研究。首先,本文建立了基于fully-kinetic PIC-MCC(質(zhì)點網(wǎng)格法-蒙特卡洛碰撞法)算法的二維軸對稱模型來對霍爾推進(jìn)器放電通道內(nèi)的物理過程進(jìn)行數(shù)值模擬,該程序模型包括三部分:計算模型的建立及參數(shù)設(shè)置,等離子體模擬程序以及腐蝕計算程序。其中,由于PIC算法計算量巨大,通常采用縮放粒子質(zhì)量以及增大介電常數(shù)的方法來加快計算收斂,本文通過縮小不同倍數(shù)的重粒子質(zhì)量探究了縮放粒子質(zhì)量這種加速方法對霍爾推進(jìn)器穩(wěn)定形態(tài)物理參數(shù)的影響,并根據(jù)模擬結(jié)果選擇了合適的縮放倍數(shù)。其次,低頻振蕩是霍爾推進(jìn)器工作狀態(tài)中觀察到的一種放電電流自發(fā)震蕩的現(xiàn)象。新型霍爾推進(jìn)器在原有霍爾推進(jìn)器的基礎(chǔ)上增加了緩沖腔,實驗證明緩沖腔的增加有效抑制了放電通道的低頻振蕩。本文的主要模擬工作就基于霍爾推進(jìn)器放電通道內(nèi)低頻振蕩現(xiàn)象的抑制來展開,通過在原子入射時增加不同的離子數(shù)來模擬不同預(yù)電離的等離子體,然后將不同預(yù)電離率下得到的放電電流進(jìn)行快速傅里葉變換得到震蕩頻譜,并分析預(yù)電離與低頻振蕩之間的相互關(guān)系。此外,本文還模擬了SPT-100型Hall推進(jìn)器的壁面腐蝕過程,探究了預(yù)電離對推進(jìn)器壁面腐蝕的影響,其中壁面腐蝕的速率是根據(jù)壁面材料的濺射產(chǎn)額公式計算得出的。通過給出緩沖區(qū)不同的預(yù)電離率,分析與之相對應(yīng)的預(yù)電離率作用下器壁腐蝕演化的規(guī)律。研究結(jié)果表明,隨著預(yù)電離率的逐漸增大,霍爾推進(jìn)器放電通道內(nèi)的低頻振蕩現(xiàn)象有所減弱,但是放電通道的壁面腐蝕狀況卻也隨之增加。因此,基于預(yù)電離能夠抑制低頻振蕩卻加劇腐蝕的特性,在進(jìn)行新一代推進(jìn)器的研發(fā)過程中要合理選擇預(yù)電離率以提高推進(jìn)器的綜合性能和壽命。
[Abstract]:Hall thruster is a device which uses orthogonal electromagnetic field to realize atomic ionization and particle acceleration of working fluid. Because of its high efficiency, high specific impulse and long life, Hall thruster is a kind of device. In recent years, it has been widely used in deep space exploration and micro satellite attitude control. However, with the development of spacecraft missions, the stability of the working life and working state of Hall thrusters is becoming more and more important. The experimental results show that preionization can affect the physical process in the discharge cavity and the physical parameters in the steady state, but no systematic analysis has been done on the specific influence process and the determination of the preionization rate. In this paper, the low frequency oscillation of preionization object and the wall corrosion of buffer cavity are studied. Firstly, a two-dimensional axisymmetric model based on fully-kinetic PIC-MCC (Particle mesh method-Monte Carlo collision) algorithm is established to simulate the physical process in the discharge channel of Hall thruster. The program model consists of three parts: the establishment of the calculation model and parameter setting, the plasma simulation program and the corrosion calculation program. The PIC algorithm usually uses the methods of scaling the particle mass and increasing the dielectric constant to speed up the convergence of the calculation. In this paper, the effect of scaling particle mass on the physical parameters of stable morphology of Hall thruster is investigated by reducing the mass of heavy particles of different times, and the appropriate scaling times are selected according to the simulation results. Secondly, low frequency oscillation is a kind of spontaneous oscillation of discharge current observed in the working state of Hall thruster. The new type of Hall thruster increases the buffer cavity on the basis of the original Hall thruster. The experiment shows that the increase of the buffer cavity effectively suppresses the low frequency oscillation of the discharge channel. The main simulation work in this paper is based on the suppression of the low frequency oscillation in the Hall propeller discharge channel. Different preionized plasma are simulated by increasing the number of ions when the atom is incident. Then the discharge current obtained under different preionization rates is analyzed by fast Fourier transform and the correlation between preionization and low frequency oscillation is analyzed. In addition, the wall corrosion process of SPT-100 Hall thruster is simulated, and the influence of preionization on the wall corrosion of the propeller is investigated. The rate of wall corrosion is calculated according to the sputtering yield formula of the wall material. By giving different preionization rates of buffer zone, the law of corrosion evolution of the vessel wall under the action of corresponding preionization rate is analyzed. The results show that with the increase of preionization rate, the low frequency oscillation in the Hall propeller discharge channel weakens, but the wall corrosion of the discharge channel increases. Therefore, based on the characteristic that preionization can suppress the low frequency oscillation but aggravate the corrosion, the preionization rate should be reasonably selected in the research and development of the new generation thruster in order to improve the comprehensive performance and life of the thruster.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：V439

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