STUDIES OF ENERGY RECOVERY LINACS AT ... - CASA
STUDIES OF ENERGY RECOVERY LINACS AT ... - CASA STUDIES OF ENERGY RECOVERY LINACS AT ... - CASA
TABLE 3.1: Design system parameters of the 10 kW FEL Upgrade. Parameter Design Value Beam energy at undulator 80-210 MeV Average beam current 10 mA Bunch charge 135 pC Bunch repetition rate up to 74.85 MHz Normalized emittance (rms) 13 mm-mrad Bunch length at undulator (rms) 200 fs Peak Current 270 A FEL extraction efficiency 1% ∆E/E before undulator (rms) 0.5% ∆E/E after undulator (full) 10% CW FEL power 10 kW displayed in Fig. 3.1. The primary system parameters (design values) are listed in Table 3.1. Because the experimental measurements described in Chapters 5, 6 and 7 were performed with the Driver, this chapter presents the required conditions for lasing, from the standpoint of the electron beam, and how these conditions are satisfied in the FEL Driver. Reduced to its primary objective, the Driver must generate a short bunch (high peak current) at the undulator and energy compress and energy recover the large longitudinal phase space of the spent electron beam following the undulator [49]. The injector is designed to generate a long bunch with low momentum spread. The objective of the Driver is to rotate the longitudinal phase space 90 ◦ to create a short bunch at the undulator. Following the undulator, the longitudinal phase space must be rotated back by 90 ◦ to energy compress the beam which has ac- quired a large momentum spread. These longitudinal phase space manipulations are achieved by accelerating the bunches off-crest through the linac to impart a phase-energy correlation. Rotation of the phase space to an upright ellipse at the undulator is accomplished with a proper choice of the momentum compaction (the 63
FIG. 3.1: Schematic of the 10 kW FEL Upgrade Driver. M56 transfer matrix element) in the first 180 ◦ bend and in a downstream magnetic chicane. Similar longitudinal phase space manipulations are used to properly man- age the beam after the undulator to the beam dump. Details of this process are described in Section 3.5. The driver can be thought of as being comprised of an injector and injection line, a linac section and a recirculator. A brief description of each section follows. 64
- Page 31 and 32: Despite its success, this method of
- Page 33 and 34: design parameters, most notably ach
- Page 35 and 36: 1.4.2 Machine Optics The second cat
- Page 37 and 38: analytic model elucidates many impo
- Page 39 and 40: CHAPTER 2 CEBAF with Energy Recover
- Page 41 and 42: FIG. 2.1: Energy versus average cur
- Page 43 and 44: FIG. 2.3: Additional hardware insta
- Page 45 and 46: FIG. 2.4: A picture of the energy r
- Page 47 and 48: dipoles and beam diagnostics such a
- Page 49 and 50: FIG. 2.7: Horizontal (red) and vert
- Page 51 and 52: FIG. 2.8: Illustration of the cryom
- Page 53 and 54: linac and θNL is the RF phase. The
- Page 55 and 56: 2.4 Transverse Emittance One of the
- Page 57 and 58: where σ2 is the rms beam size meas
- Page 59 and 60: eams. The effects of varying the qu
- Page 61 and 62: FIG. 2.12: A typical wire scan near
- Page 63 and 64: quadratic fit and a multiple regres
- Page 65 and 66: ting the data is difficult. Without
- Page 67 and 68: primary source of error is measurin
- Page 69 and 70: identified, although the phase dela
- Page 71 and 72: TABLE 2.3: Comparison of Twiss para
- Page 73 and 74: the results of the fits. The vertic
- Page 75 and 76: FIG. 2.18: Schematic illustrating t
- Page 77 and 78: FIG. 2.19: The GASK signal measured
- Page 79 and 80: FIG. 2.20: The measured normalized
- Page 81: CHAPTER 3 The Jefferson Laboratory
- Page 85 and 86: FIG. 3.2: Layout of the DC photocat
- Page 87 and 88: accelerating gradient at the front
- Page 89 and 90: eason for making the endloops achro
- Page 91 and 92: FIG. 3.7: Illustration of path leng
- Page 93 and 94: 3.5 Longitudinal Dynamics This sect
- Page 95 and 96: FIG. 3.9: The effect of a thin focu
- Page 97 and 98: Under the constraint that each orde
- Page 99 and 100: form of beam breakup not only occur
- Page 101 and 102: 4.1 The Pillbox Cavity Although the
- Page 103 and 104: FIG. 4.2: Electric field (red) and
- Page 105 and 106: where the full 4×4 transfer matrix
- Page 107 and 108: The threshold is inversely proporti
- Page 109 and 110: 4.3 BBU Simulation Codes: Particle
- Page 111 and 112: 6. The second pass beam bunch then
- Page 113 and 114: which excites it. The BBU instabili
- Page 115 and 116: Equation (4.41) is a dispersion rel
- Page 117 and 118: FIG. 4.4: Output from MATBBU showin
- Page 119 and 120: FIG. 4.5: Setup for measuring cavit
- Page 121 and 122: Consequently, depending on the exte
- Page 123 and 124: The projection of the beam displace
- Page 125 and 126: TABLE 4.1: Experimental measurement
- Page 127 and 128: FIG. 4.10: A plot showing the effec
- Page 129 and 130: these cryomodules. Modes from these
- Page 131 and 132: CHAPTER 5 Experimental Measurements
FIG. 3.1: Schematic of the 10 kW FEL Upgrade Driver.<br />
M56 transfer matrix element) in the first 180 ◦ bend and in a downstream magnetic<br />
chicane. Similar longitudinal phase space manipulations are used to properly man-<br />
age the beam after the undulator to the beam dump. Details of this process are<br />
described in Section 3.5.<br />
The driver can be thought of as being comprised of an injector and injection<br />
line, a linac section and a recirculator. A brief description of each section follows.<br />
64
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