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Experience with the ground test accelerator beam-measurement instrumentation

1994; American Institute of Physics; Linguagem: Inglês

10.1063/1.46958

1935-0465

J.D. Gilpatrick, K. F. Johnson, R. Connolly, J. Power, Chris Rose, O.R. Sander, Robert E. Shafer, D.P. Sandoval, V. W. Yuan,

Laser-Plasma Interactions and Diagnostics

During the past two years, the Ground Test Accelerator (GTA) has used a variety of off‐ and on‐line beam diagnostic measurements to understand and verify the transverse and longitudinal phase space characteristics of a 35‐mA, low‐energy (2.5‐ to 3.2‐MeV) H−‐beam. For the transverse phase‐space characterization measurements, a slit and collector device samples of the x−x’ and y−y’ phase space, to determine the transverse emittance and Courant–Snyder parameters. The longitudinal phase‐space data are acquired by a laser neutralization technique developed at Los Alamos know as the laser induced neutralization diagnostics approach (LINDA). The transverse and longitudinal phase‐space centroids of the low‐energy, 425‐MHz‐bunched beam are directly measured using the microstrip probe systems. Beam current and transmission are measured by various toroid systems. Beam‐loss‐detection techniques have just been installed and a non‐interceptive beam‐profile measurement has been commissioned. All of these measurement systems have had their share of successes and challenges. For example, while the microstrip‐system’s energy, phase, and intensity measurements operated successfully, their beam‐position‐measurement calibrations did not agree with either wire calibration data or measured slit‐and‐collector beam‐centroid data due to perturbations to the beam’s image‐current distributions and low‐β effects of the probe’s position‐detection sensitivity. This paper describes the measurement systems and commissioning team’s experiences using these systems.