對於各項研究愈趨微細的今日，經由觀察原子、分子的結構分析來瞭解其物理及化學性質是一件不可或缺的研究步驟，傳統同步輻射光源顯然已不符需求，然而自由電子雷射因擁有波長可調變性、高平均功率、高瞬間功率及高亮度輻射等特點，現已成為全球各加速器實驗室主要的研究題材之一。國家同步輻射研究中心於 2003 年依據國內用戶對於光源使用的需求提出窄線寬高平均功率遠紅外光自由電子雷射計畫，在初步設計討論中，對於電子束品質要求及整體傳輸線安排做了概略性的探討，訂出各項基本參數；然而，對於電子束在這條件要求下的運動行為並無過多的探討。本論文中，我們將藉由電腦模擬，分析電子束在超導線型加速器中的運動行為，並對預設各項電子束參數做一有系統的檢驗，驗證設計參數的可行性並給予適度的修正；在低能量入射的電子束中，空間電荷所造成的影響是一個不可忽略的問題，我們也藉由電腦程式的模擬，分析空間電荷所造成的影響，找出超導線型加速器中，入射條件的要求，並與高能量入射的電子束運動行為比較，藉此瞭解兩種情況下電子束運動行為的異同。論文中也對模擬工具PARMELA 和 SUPERFISH 做了簡短的介紹，對其計算結果輔以理論驗證確認準確性；關於由注射器後至線型加速器末端間的傳輸線設計，亦做了初步探討；最後，我們也完成了超導線型加速器對於電子束各項入射要求的確認，找到可容許的參數誤差範圍，並對前端注射系統提出設計上的建議。

In NSRRC narrow-bandwidth IR FEL proposal, an electron beam with high bunch charge will be injected into an energy recovered Superconducting linac system. In such situation, an intense space charge force acting on individual electrons within bunches; final beam quality will be dominated by such space charge field especially at lower energy injection. The TESLA 9-cell superconducting cavity will be used as the main linac. In this study, we will use SUPERFISH and PARMELA to study the motion of space charge dominated beams in such linac and examine the feasibility of preliminary beam parameters for the FEL. In addition to the study of the influence of space charge effect, we also examine the conditions for linac injection. The characteristic of transport system during acceleration are also studies systematically. A solenoid will be used as an element to match beam motion in the linac, with appropriate solenoid strength setting, beam matching condition can be achieved and emittance growth due to mismatching can be avoided. These results in comparison with theoretical calculation will be shown.

[1] LCLS Design Study Report, Report SLAC-R-521 (1998)
[2] G. R. Neil, et al., “Sustained Kilowatt Lasing in a Free Electron Laser with Same-Cell Energy Recovery,” Phys. Rev. Lett. 84, 662 (2000)
[3] Patrick G. O’Shea and Henry P. Freund, Science 292, 1853 (2001)
[4] Charles A Brau, Free-electron Lasers, Boston Academic Press, 1990.
[5] Hasan Padamsee, Jens Knobloch, Tom Hays, RF superconductivity for accelerators, Wiley, New York, 1998.
[6] W.K.Lau, C.W.Chen, et al., “PRELIMINARY DESIGN OF A SYNCHRONIZED NARROW BANDWIDTH FEL FOR TAIWAN LIGHT SOURCE” Proceedings of the 2004 FEL Conference, 262-265
[7] S.Y.Lee, Accelerator Physics, World Scientific, NJ, 1999.
[8] M. Reiser, Theory and Design of Charged Particle Beams, Wiley, New York, 1994.
[9] J. B. Rosenzweig, Phys. Rev. E. 47, 2031 (1993)
[10] J. B. Rosenzweig, Phys. Rev. E. 49, 1599 (1994)
[11] J. B. Rosenzweig, Phys. Rev. E. 55, 7565 (1997)
[12] R. L. Gluckstern, Linear Accelerators (ed. P. Lapostolle and A. Septier), North-Holland, Amsterdam, 1967.
[13] Bruce Carlsten, Los Alamos National Laboratory Report, LA-UR-04-8900 (2004)
[14] L. M. Young, “PARMELA,” Los Alamos National Laboratory report LA-UR-96-1835 (Revised April 22, 2003).
[15] J. H. Billen and L. M. Young, “Poisson Superfish,” Los Alamos National Laboratory report LA-UR-96-1834 (Revised February 6, 2003).
[16] H. Y. Chen, “Investigation of Space charge beam Dynamics in a Photo-cathode Superconducting RF Gun,” University of Tsin-Hua, Taiwan master thesis, 2005
[17] T. P. Wangler, Principles of RF Linear Accelerators, Wiley, New York, 1998.
[18] R. Wanzenberg, TESLA Report, 2001-33. 2001.
[19] B. Aune et al., Phys. Rev. ST., 3, 092001 (2000).
[20] N. Baboi, Stdies on higher Order Modes in Accelerating Structures for Linear Colliders, Ph.D Thesis, University of Hamburg, 2001.
[21] D. Janssen and V. Volkov, Nucl. Instr. and Meth. A 452, 34 (2000).
[22] D. Janssen et al., Nucl. Instr. and Meth. A 528, 305 (2004).