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Last Name: Yu
Full Name: Yu, D.
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6 papers
| title: | Development of an X-Band PWT Photoinjector |
| format: | conference procceeding |
| conference: | 2001 Particle Accelerator Conference |
| year: | 2001 |
| 5 authors: | | | | | |
| abstract: | Development of an X-band Plane-Wave-Transformer (PWT), integrated photoinjector continues. Modifications of the end-cell design in this two-section device allow for simultaneous frequency and phase tuning of the accelerating field, thus preventing deceleration at the drift region that separates the two sections. The Los Alamos version of PARMELA is used to determine the expected performance parameters from the final design. |
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| title: | The development of S-band plane wave transformer photoinjector |
| format: | conference procceeding |
| conference: | 1999 Particle Accelerator Conference |
| year: | 1999 |
| 11 authors: | | | | | | | | | | | |
| abstract: | An integrated S-band RF photoinjector based on the plane wave transformer (PWT) is being built in the Particle Beam Physics Laboratory at UCLA in collaboration with DULY Research. This novel structure integrates a photocathode directly into a PWT linac making the structure simple and compact. Due to the strong coupling between each adjacent cell, this structure is relatively easy to fabricate and operate. This photoinjector can provide high brightness beams at energies of 15 to 20 MeV, with emittance less than 1 mm-mrad at charge of 1 nC. These short-pulse beams can be used in various applications: space charge dominated beam physics studies, plasma lenses, plasma accelerators, free-electron laser microbunching techniques, and SASEFEL physics studies. It will also provide commercial opportunities in chemistry, biology and medicine. The present status of the PWT photoinjector including fabrication and cold test to characterise the structure is described. RF system and photocathode drive laser system are also discussed. |
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| title: | A permanent-magnet focused X-band photoinjector |
| format: | conference procceeding |
| conference: | 1999 Particle Accelerator Conference |
| year: | 1999 |
| 8 authors: | | | | | | | | |
| abstract: | A Plane-Wave-Transformer (PWT), integrated photoinjector operating at an X-band frequency (8.547GHz) is being developed by DULY Research Inc. in a DOE SBIR project, in collaboration with UCLA and UCD/ILSA. Upward frequency scaling from an S-band PWT photoinjector would result in a compact photoinjector with unprecedented brightness. Challenging technological innovations are required at X-band. In particular, water cooling capacity, mechanical support strength, and materials properties do not scale linearly with frequency. Instead of using large solenoids, we have successfully designed the required focusing for an X-band PWT using a compact, permanent magnet system. Also described in this paper is a system design of the X-band photoinjector, including the RF system and the cooling/support of the PWT structure. |
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| title: | The effects of RF asymmetries on photoinjection beam quality |
| format: | conference procceeding |
| conference: | 1999 Particle Accelerator Conference |
| year: | 1999 |
| 4 authors: | | | | |
| abstract: | A general multipole-based formalism to study the effects of RF asymmetries on the production of ultra-high brightness beam is presented, which employs both analytical and computational techniques. These field asymmetries can cause the degradation of beam emittance due to time dependent and nonlinear focusing effects. Two cases of interest are examined: the dipole asymmetry produced by a coupling slot in a standard high gradient RF gun, and the higher multipole content introduced by the support/cooling rods in a PWT structure. Practical implications of our results, as well as comparison to cold test and beam-based experimental tests, are discussed. (8 References). |
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| title: | Beam dynamics in an integrated plane wave transformer photoinjector at S and X-band |
| format: | conference procceeding |
| conference: | 1997 Particle Accelerator Conference |
| year: | 1998 |
| 6 authors: | | | | | | |
| abstract: | The beam dynamics of an integrated S-band RF photoinjector based on the plane wave transformer (PWT) concept, proposed as part of an SBIR collaboration between UCLA and DULY Research, are studied. The design, which calls for an 11.5 cell structure run at a peak accelerating field of 60 MV/m and uses a compact solenoid around the initial 2.5 cells, is based on a recently developed theory of emittance compensation. It calls for matching the beam onto a generalized equilibrium envelope, which produces a beam which diminishes in transverse size monotonically with acceleration. This condition minimizes the emittance, which is 1 mm-rad at Q=1 nC. This design is also scaled to produce nearly identical performance at X-band, giving an injector appropriate to running an FEL at the SLAC NLCTA. These designs are insensitive to RF emittance increase, allowing a wide choice of injection phase, and the option to compress the emitted pulse. (8 References). |
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| title: | A plane-wave-transformer photoelectron linac |
| format: | conference procceeding |
| conference: | 1997 Particle Accelerator Conference |
| year: | 1998 |
| 7 authors: | | | | | | | |
| abstract: | We develop a novel photoelectron linear accelerator using a plane wave transformer (PWT) design. In this design, the input RF power is coupled to the accelerating cavities via a large concentric manifold cavity. The scheme makes possible very strong coupling between the accelerating cells, and relaxes manufacturing tolerances. The compact photoelectron linac integrates a photocathode directly into a PWT linac structure, and eliminates the drift space between a photoinjector and the linac which would otherwise lengthen the electron bunches. Using an emittance compensation scheme, the PWT photoelectron linac produces a high-brightness beam. We have demonstrated by simulations the feasibility of a 20 MeV PWT photoelectron linac design with a set of eleven iris-loaded disks suspended and cooled by four water tubes inside a large cylindrical tank. (5 References). |
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