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Last Name: Colby
Full Name: E. Colby
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13 papers
| title: | ORION: An Advanced Accelerator Facility at SLAC |
| format: | conference procceeding |
| conference: | 2001 Particle Accelerator Conference |
| year: | 2001 |
| 13 authors: | | | | | | | | | | | | | |
| abstract: | Extending the center-of-mass energy frontier for high-energy physics depends on the research and development that is conducted now in the area of advanced accelerator physics and technology. In this article, we present the design and beam dynamics simulations for the emittance-compensated, RF photoinjector of the ORION Facility. (4 References). |
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| title: | Experimental testing of the TTF RF photoinjector |
| format: | conference procceeding |
| conference: | 1997 Particle Accelerator Conference |
| year: | 1998 |
| 7 authors: | | | | | | | |
| abstract: | Results from the experimental testing of the prototype TESLA Test Facility (TTF) RF photoinjector are summarized. Preliminary measurements of the performance of the injector indicate that, with refinement, the design values for the transverse emittances (20 x 20 pi mm-mr) are not unrealistic, with uncompressed transverse emittances of 40 pi mm mr having been obtained under somewhat less ideal circumstances than those simulated. Preliminary pulse length measurements with and without the pulse compressor suggest pulse compression, but further study is required. |
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| title: | Towards a plasma wake-field acceleration-based linear collider |
| format: | conference procceeding |
| conference: | ICFA Second Generation Plasma Acceleration Workshop |
| year: | 1998 |
| 5 authors: | | | | | |
| abstract: | A proposal for a linear collider based on an advanced accelerator scheme, plasma wake-field acceleration in the extremely nonlinear regime, is discussed. In this regime, many of the drawbacks associated with preservation of beam quality during acceleration in plasma are mitigated. The scaling of all beam and wake parameters with respect to plasma wavelength is examined. Experimental progress towards high-gradient acceleration in this scheme is reviewed. We then examine a linear collider based on staging of many modules of plasma wake-field accelerator, all driven by a high average current, pulse compressed, RF photoinjector-fed linac. Issue of beam lending, efficiency, optimized stage length, and power efficiency are discussed. A proof-of-principle experimental test of the staging concept at the Fermilab test facility is discussed. |
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| title: | Design, Construction and Testing of a Radiofrequency Electron Photoinjector for the Next Generation Linear Collider |
| format: | thesis |
| year: | 1997 |
| 1 author: | |
| abstract: | The design of a high bunch charge (8 nC), low emittance (< 20 nn-mr) radiofrequency electron photoinjector matched to the requirements of the TESLA Test Facility is presented. A 1.625-cell iris-coupled pi-mode structure with high average accelerating gradient is chosen for its high shunt, impedance, simplicity, and ability to accomodate an externally mounted solenoid for simultaneous beam divergence control and emittance compensation. A novel split-solenoid focussing assembly is employed, allowing emittance compensated beam extraction over a wide range of gun gradients. Beam optics are optimized for an overall injector consisting of the electron gun followed by one linac capture section (providing acceleration to 18 MeV), and a dipole chicane for magnetic bunch compression to achieve a bunch length sigma_z of 1 mm. Analytic and simulation work yielding a space charge emittance compensated gun design in a new high charge regime is detailed. Experimental measurements made on a prototype gun and injector at the Argonne Wakefield Acclerator Facility are detailed. Experimental results indicate a beam of 8 nC charge with bunch length ~ 1.1 mm has been produced at emittances of less than 60 x 60 pi mm-mr at an energy of 16 MeV with an energy spread of 240 keV. Experimental results, although in significant disagreement (by a factor of two) with initial simulations (which assume idealized laser properties), are in fair agreement with simulations carried out using the measured performance of the laser. |
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| title: | A Linear Collider Based on Nonlinear Plasma Wake-field Acceleration |
| format: | conference procceeding |
| conference: | Summer Study on New Directions for High Energy Physics |
| year: | 1997 |
| 3 authors: | | | |
| abstract: | A proposal for a linear collider based on an advanced accelerator scheme, plasma wake-field acceleration in the extremely nonlinear regime is discussed. In this regime, many of the drawbacks associated with preservation of beam quality during acceleration in plasma are mitigated. Experimental progress towards high-gradient acceleration in this scheme is reviewed. We then examine a linear collider based on staging of many modules of plasma wake-field accelerator, all driven by a high average current, pulse compressed, rf photoinjector-fed linac. Issues of beam loading, efficiency, optimized stage length, and power efficiency are discussed. A proof-of-principle experimental test of the staging concept and the Fermilab Test Facility is discussed. |
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| title: | Pulse compression in radio frequency photoinjectors: applications to advanced accelerators |
| format: | conference procceeding |
| conference: | Workshop on Second Generation Plasma Accelerators |
| year: | 1996 |
| 3 authors: | | | |
| abstract: | While RF photoinjectors are an excellent source of high brightness electron beams, there are constraints to tying together the expected emittance and peak current performance of a given photoinjector system. These constraints, which arise from the complicated dynamics of the electrons due to the interplay of RF and space-charge forces within the photoinjector, tend to favor lower peak current operation. For some ultimate uses of photoinjector beams, such as linear collider test beams, wakefield accelerators, and free-electron lasers (FEL's), one may desire much higher peak currents. In this case, an inexpensive and reliable method for producing extremely short high-current electron bunches is to use magnetic compression. We examine this scheme analytically and by computer simulation. Many applications are illustrated, including the TESLA Test Facility/FEL injector, ultra-high current beams for plasma wakefields and generation of femtosecond electron pulses for injection ultra-high current beams for injection into short wavelength laser-based accelerators. It is shown that the injection timing jitter associated with the laser can be nearly eliminated using this scheme, making it an indispensable component in many of the advanced accelerator injectors we consider. |
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| title: | Design and Construction of High Brightness RF Photoinjectors for TESLA |
| format: | conference procceeding |
| conference: | 1995 Particle Accelerator Conference |
| year: | 1995 |
| 6 authors: | | | | | | |
| abstract: | The design, construction and testing of a high brightness high bunch charge RF photoinjectormatching the requirements of the TESLA Test Facility is discussed. Engineering design work, the results of cold test measurements, and the planned experimental program are presented. Conceptual design work leading to an advanced high-brightness asymmetric emittance RF photoinjector for application to TESLA500 is also briefly discussed. |
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| title: | Charge and Wavelength Scaling of RF Photoinjectors: A Design Tool |
| format: | conference procceeding |
| conference: | 1995 Particle Accelerator Conference |
| year: | 1995 |
| 2 authors: | | |
| abstract: | The optimum design of an emittance compensated rf photoinjector is very complicated and time-consuming, relying heavily on multi-particle simulations without good analytical models as a guide. Emittance compensated designs which have been developed, however, can be used to generate other designs with no additional effort if the original design is scaled correctly. This paper examines the scaling of rf photoinjector design with respect to charge and wavelength, and presents emittance and brightness scaling laws for these variables. Parametric simulation studies are presented to illustrate these scaling laws. A practical design for the TESLA FEL rf photo-injector is developed using these scaling techiniques. |
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| title: | Pulse Compression in RF Photoinjectors: Applications to Advanced Accelerators |
| format: | preprint |
| year: | 1995 |
| 3 authors: | | | |
| abstract: | While rf photoinjectors are an excellent source of high brightness electron beams, there are constraints tying together the expected emittance and peak current performance of a given photoinjector system. These constraints, which arise from the complicated dynamics of the electrons due to the interplay of rf and space-charge forces within the photoinjector, tend to favor lowe peak current operation. For some ultimate uses of photoinjector beams, such as linear collider test beams, wake-field accelerators and FELs, one may desire much higher peak currents. In this case, an inexpensive and reliable method for producing extramely short, high-current electron bunches is to use magnetic compression. We examine this scheme alalytically and by computer simulation. Many applications are illustrated, including the TESLA Test Facility/FEL injector, ulta-high current beams for plasma wake-fields, and generation of femtosecond electron pulses for injection into short wavelength laser-based accelerators. It is show that the injection timing jitter associated with the laser can be nearly eliminated using this scheme, making it an indispensable component in many of the advanced acclerator injectors we consider. |
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| title: | Charge and Wavelength Scaling of RF Photoinjector Designs |
| format: | unknown |
| year: | September 21, 1994 |
| 2 authors: | | |
| abstract: | The optimum design of an emittance compensated rf photoinector is very complicated and time-consuming, relying heavily on multi-particle simulations without good analytical models as a guide. Emittance compensated designs which have been developed, however, can be used to generate other designs with no additional effort if the original design is scaled correctly. This paper examines the scaling of rf photoinjector design with reqpect to charge and wavelength, and presents emittance and brightness scaling laws for these variables. Parametric simulation studies are presented to illustrate these scaling laws. Deviations from scaling and practical considerations are also discussed. |
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| title: | High Brightness Symmetric Emittance RF Photoinjector Preliminary Design Report |
| format: | preprint |
| year: | September 15, 1994 |
| 3 authors: | | | |
| abstract: | A preliminary design for a high bunch charge (8 nC), low emittance (> 20 mm-mr) radiofrequency electron photoinjector matched to the requirements of the Tesla Test Facility is presented. A 1.5 cell iris coupled pi-mode structure with high average accelerating gradient is chosen for its high shunt impedance, simplicity, and ability to accommodate an externally mounted solenoid for simultaneous beam divergence control an demittance compensation. Beam optics are optimized for an overall injector consisting of the electron gun followed by one linac capture section, a dipole chicane for magnetic bunch compression to achieve a bunch length corresponding to sigma_z = 1 mm. Electrical and beam dynamical aspects of the photoinjector design are presented. A description of the proposed experimental program is included. |
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| title: | Design of High Brightness Symmetric and Asymmetric Emittance RF Photoinjectors for TESLA |
| format: | conference procceeding |
| conference: | 6th Advanced Accelerator Concepts Workshop |
| year: | 1995 |
| 3 authors: | | | |
| abstract: | Development work leading to emittance-compensated symmetric emittance and asymmetric emittance RF photoinjectors is discussed. A mature design for a symmetric emittance photoinjector is described, and current work leading to an asymmetric design is detailed. An experimental program to characterize both injectors and to explore the physical mechanism of emittance compensation using the facilities of the Argonne Wakefield Accelerator is outlined. (15 References). |
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| title: | Design of a high duty cycle, asymmetric emittance RF photocathode injector for linear collider applications |
| format: | conference procceeding |
| conference: | 1993 Particle Accelerator Conference |
| year: | 1993 |
| 4 authors: | | | | |
| abstract: | One of the attractive features of the superconducting approach to linear collider design is that the transverse emittances demanded are much larger than in normal conducting schemes. For TESLA design parameters, the damping rings appear to be relatively large and expensive, and it is therefore of some interest to look into alternative sources. For electrons, a promising source candidate is an RF photocathode. In this paper, we present conceptual design work towards development of an asymmetric emittance RF photocathode source which can operate at the TESLA repetition rates and duty cycle, and is capable of emitting beams with the required emittances and charge per pulse. (7 References). |
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