D. Vanecek

Electron-beam diagnostic for space-charge measurement of an ion beam

An electron beam diagnostic system for measuring the charge distribution of an ion beam without changing its properties is presently under development for Heavy Ion Fusion (HIF) beam physics studies. Conventional diagnostics require temporary insertion of sensors into the beam, but these capture it, or significantly alter its properties. In this new diagnostic a low energy, low current electron beam is scanned transversely across the ion beam; the measured electron beam deflection is used to calculate the line-integrated charge density of the ion beam, assuming at present a circular charge distribution that is functionally dependent only on radius. The initial application of this diagnostic is being made to the Neutralized Transport Experiment (NTX), which is exploring the physics of space charge dominated beam focusing through neutralizing plasma onto a small spot. The diagnostic system is able to scan an ion beam of up to 3 cm radius. Design and performance of this diagnostic system is presented.

Stacked insulator induction accelerator gaps

Stacked insulators, with alternating layers of insulating material and conducting film, have been shown to support high surface electrical field stresses. We have investigated the application of the stacked insulator technology to the design of induction accelerator modules for the Relativistic-Klystron Two-Beam Accelerator program. The RF properties of the accelerating gaps using stacked insulators, particularly the impedance at frequencies above the beam pipe cutoff frequency, are investigated. Low impedance is critical for Relativistic-Klystron Two-Beam Accelerator applications where a high current, bunched beam is transported through many accelerating gaps. An induction accelerator module designs using a stacked insulator is presented.

Engineering conceptual design of the relativistic klystron two-beam accelerator based power source for 1 TeV Next Linear Collider

Ultra-high gradient radio frequency linacs require network current. Efficient and reliable power sources. The induction linac has proven to be a reliable source of low energy, high current and high brightness electron beams. The low energy beam is bunched, transported through resonant transfer cavities in which it radiates microwave energy that is coupled to an adjacent high energy accelerator. The low energy beam is maintained at a constant energy by periodic induction accelerator cells. This paper describes the engineering aspects of the induction accelerator based relativistic klystron. The physics issues are covered in another paper at this conference.

Heavy ion fusion 2 MV injector

A heavy-ion-fusion driver-scale injector has been constructed and operated at Lawrence Berkeley Laboratory. The injector has produced 2.3 MV and 950 mA of K/sup +/, 15% above original design goals in energy and current. Normalized edge emittance of less than 1 /spl pi/ mm-mr was measured over a broad range of parameters. The head-to-tail energy flatness is less than /spl plusmn/0.2% over the 1 /spl mu/s pulse.

Diagnostics for a 1.2-kA, 1-MeV, electron induction injector

We are constructing a 1.2-kA, 1-MeV, electron induction injector as part of the RTA program, a collaborative effort between LLNL and LBNL to develop relativistic klystrons for Two-Beam Accelerator applications. The RTA injector will also be used in the development of a high-gradient, low-emittance, electron source and beam diagnostics for the second axis of the Dual Axis Radiographic Hydrodynamic Test (DARHT) Facility. The electron source will be a 3.5``-diameter, thermionic, flat-surface, m-type cathode with a maximum shroud field stress of approximately 165 kV/cm. Additional design parameters for the injector include a pulse length of over 150-ns flat top (1% energy variation), and a normalized edge emittance of less than 200 {pi}-mm-mr. Precise measurement of the beam parameters is required so that performance of the RTA injector can be confidently scaled to the 4-kA, 3-MeV, and 2-microsecond pulse parameters of the DARHT injector. Planned diagnostics include an isolated cathode with resistive divider for direct measurement of current emission, resistive wall and magnetic probe current monitors for measuring beam current and centroid position, capacitive probes for measuring A-K gap voltage, an energy spectrometer, and a pepper-pot emittance diagnostic. Details of the injector, beam line, and diagnostics are presented.

Design of a 1-MV induction injector for the Relativistic Klystron Two-Beam accelerator

A Relativistic Klystron Two-Beam Accelerator (RK-TBA) is envisioned as a RF power source upgrade of the Next Linear Collider. Construction of a prototype, called the RTA, based on the RK-TBA concept has commenced at the Lawrence Berkeley National Laboratory. This prototype will be used to study physics, engineering, and costing issues involved in the application of the RK-TBA concept to linear colliders. The first half of the injector, a 1 MeV, 1.2 kA, 300 ns induction electron gun, has been built and is presently being tested. The design of the injector cells and the pulsed power drive units are presented in this paper.

A systems study of an RF power source for a 1 TeV next linear collider based upon the relativistic‐klystron two‐beam accelerator

A systems study, including physics, engineering, and costing, has been conducted to assess the feasibility of a relativistic‐klystron two‐beam‐accelerator (RK‐TBA) system as a RF power source candidate for a 1 TeV linear collider. Several key issues associated with a realizable RK‐TBA system have been addressed, and corresponding schemes have been developed and examined quantitatively. A point design example has been constructed to present a concrete conceptual design which has acceptable transverse and longitudinal beam stability properties. The overall efficiency of RF production for such a power source is estimated to be 36%, and the cost of the full system is estimated to be less than 1 billion dollars.