發(fā)布時(shí)間：2024-11-03 00:03

　　超冷等離子體是一種特殊的強(qiáng)耦合等離子體,其中離子和電子的溫度遠(yuǎn)低于傳統(tǒng)等離子體,因而其具有相對(duì)極長(zhǎng)的演化時(shí)間,并且體現(xiàn)出強(qiáng)的庫(kù)侖耦合效應(yīng)。通過超冷等離子體研究強(qiáng)耦合效應(yīng)還有許多優(yōu)點(diǎn),例如:等離子體初始狀態(tài)可控、離子溫度低而且演化時(shí)間尺度長(zhǎng)、相對(duì)成熟的實(shí)驗(yàn)平臺(tái)以及寬泛可調(diào)的參數(shù)空間等等。因而,超冷等離子體為實(shí)驗(yàn)和理論研究強(qiáng)耦合等離子體物理提供了一個(gè)特殊和理想的平臺(tái)。本文主要研究超冷等離子體的產(chǎn)生動(dòng)力學(xué),實(shí)驗(yàn)通過激光電離磁光阱中冷原子的方法和冷里德堡原子自發(fā)演化的方法獲得了超冷等離子體,并在兩種實(shí)驗(yàn)方案中測(cè)量了不同條件下等離子參數(shù)的變化,重點(diǎn)討論了超冷等離子體產(chǎn)生過程中起重要作用的物理過程和機(jī)制。利用磁光阱冷卻囚禁的Rb-87原子的密度和溫度分別為10¹⁰ cm^-3和500μK。實(shí)驗(yàn)中可控制的物理參量包括:電子的初始動(dòng)能（溫度）、離子/電子的初始密度、里德堡原子能級(jí)和原子數(shù)布局、以及外加電場(chǎng)場(chǎng)強(qiáng)等。首先,我們利用光電離冷原子的方法產(chǎn)生了超冷等離子體,測(cè)量了等離子體的壽命和閾值離子數(shù)等參數(shù),并利用庫(kù)侖勢(shì)阱模型和自相似擴(kuò)散模型對(duì)實(shí)驗(yàn)結(jié)果進(jìn)行了擬合和解釋...

【文章頁(yè)數(shù)】：103 頁(yè)

【學(xué)位級(jí)別】：博士

【文章目錄】：
abstract
摘要
Chapter 1 Introduction
    1.1 Background
    1.2 Motivation
    1.3 Creation of an ultracold plasma
        1.3.1 Photoionization of cold atoms
        1.3.2 Spontaneous ionization of a dense Rydberg gas
    1.4 Theoretical study of the ultracold plasmas
    1.5 Recent advances in the ultracold plasma physics
        1.5.1 Achieving strongly coupled plasma
        1.5.2 Recent progress
    1.6 Layout of the thesis
Chapter 2 Diagnostic techniques and plasma dynamics
    2.1 Plasma diagnostics
        2.1.1 Charged particle detection
        2.1.2 Optical probes
        2.1.3 Probing by three-body recombination
        2.1.4 Other probes
    2.2 Plasma dynamics
        2.2.1 Three-body recombination and early electron dynamics
        2.2.2 Disorder-induced heating
        2.2.3 Kinetic energy oscillations
        2.2.4 Self-similar adiabatic expansion
Chapter 3 Experimental techniques
    3.1 Experimental setup
        3.1.1 Direct photoionization of laser-cooled 87Rb atoms
        3.1.2 Rydberg excitation and detection
    3.2 Laser cooling and trapping
        3.2.1 Magneto-optical trap
        3.2.2 Vacuum chamber
        3.2.3 Vacuum pumps
        3.2.4 Laser system
        3.2.5 Saturated absorption spectroscopy
        3.2.6 Data acquisition
Chapter 4 Ultracold plasma from photoionization of cold atoms
    4.1 Creation of ultracold plasma
        4.1.1 Ultracold plasma with different ionization laser energies
        4.1.2 The lifetime of the ultracold plasma
    4.2 Ultracold plasma in the direct current field environment
        4.2.1 Creation of the ultracold plasma in the DC field
        4.2.2 Ultracold plasma with different initial electron kinetic energies
        4.2.3 The dependence ultracold plasma on the direct current field
Chapter 5 Ultracold plasma from cold Rydberg gas
    5.1 Rydberg atoms
        5.1.1 Excitation of Rydberg states
        5.1.2 Detection of Rydberg atoms
    5.2 Cold Rydberg gas dynamics
        5.2.1 Angular momentum mixing
        5.2.2 n-mixing and ionizing collisions
        5.2.3 Penning ionization
    5.3 Spontaneous ionization of Rydberg gas
    5.4 Evolution of cold Rydberg gas from n P states into ultracold plasma
        5.4.1 Excitation and field ionization of the cold Rydberg gas
        5.4.2 Field ionization spectra at different evolution time
        5.4.3 Spontaneous evolution of nP Rydberg states
Chapter 6 Conclusion and future work
    6.1 Conclusion
    6.2 Future work
References
Acknowledgements
Personal Statement and Academic Achievements during the Doctoral Period
Appendix



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