W.J. Ramler

Tests on superconducting helix resonators

A niobium helix‐resonator cavity close to the frequency suitable for a heavy‐ion accelerator has been subject to an 8‐week test, including 323 h at full power (axial electric field Eax>2.5 MV/m). The cavity, with an anodically deposited protective film of Nb2O5, had a high Q and supported high fields without deterioration over the whole period during which it was subject to a moderate internally generated x‐ray dose. Properties were found to be stable against considerable thermal cycling and exposure to air. Measurement of emitted x‐ray maximum energy allowed an independent corroboration of the field measurement calibration.

A non-intercepting accelerator beam positron sensor☆

Abstract A non-intercepting beam position sensor consisting of two sets of pick-up coils, resonant tuned, are used with a differential amplifier and an oscilloscope to determine the spatial position of a pulsed beam from an electron linear accelerator. A pulsed beam of 100 mA peak can be positioned to about 0.5 mm. Recent work indicates the feasibility of using this position sensor technique with an external cyclotron beam. The design, method of construction, and performance of the linac sensor is discussed. A brief summary of the cyclotron sensor is given.

High current pulsed electron source — Van de Graaff☆

Abstract An electron gun and pulser have been developed to produce high current pulses of nanosecond duration. When mounted on the ht terminal of a 3 MeV electron Van de Graaff, 5 A pulses have been obtained for time durations of 1 to 100 ns. Corresponding beam area without external focusing is about 0.15 cm 2 .

Deflection coil for an external accelerator beam

A compound vertical and horizontal deflection coil using a motor-stator type iron core and a winding with a sinusoidal turns distribution makes a useful tool for precisely positioning, and sweeping the external beam of an accelerator. The design, method of construction, performance and characteristics of this coil are discussed.

Development and Operation of a Prototype Superconducting Linac for Heavy-Ion Acceleration

A prototype superconducting-helix accelerator is described and design considerations are discussed. The results obtained during 120 hours of beam acceleration are given. These include a wealth of practical engineering experience, the demonstration of stable operation with external phase control, and measurements of various kinds of accelerator-physics data.

Energy Degrading-Focusing of Cyclotron Beam†

The ANL 60-inch cyclotron is a fixed 10.8 MeV/nucleon accelerator. To increase machine flexibility, it was desired to obtain variable energy projectiles 25–40 feet from the accelerator without severely reducing particle number and beam definition. Sacrificing energy resolution, a focused variable energy beam can be obtained by using the technique of a foil absorption system close coupled with strong focusing provided by quadrupole magnets. The system to be described can readily degrade a deuteron or alpha beam to about 2.5 MeV/nucleon with about 5% of the original particles focused a distance of 35 feet from the accelerator 1) .

A Low Power Magnetic Channel with Dipole Compensation

A magnetic channel capable of guiding deflected 60 MeV protons through the fringing field of an AVF cyclotron without perturbing inner orbits, has been tested in a 0.394 scale model. The full scale channel will be composed of a 1010 steel cylindrical shell 3.00 in. O. D., 1.18 in. I.D., and 10 in. long with an external dipole winding extending to 5.92 in. O.D. A cosinoidal distribution of current density is approximated by dividing the winding into 16 sections, with centers about 22.5° apart, and by making No = No cos ?, where N is the number of turns in a section and ? is the altitude angle of the center of a section. Scaling the model measurements to full size, the power is 14 kW with 3/8 in. square O.D. and 1/8 in. round I.D. water-cooled copper conductors at 330 A, and the field at the midpoint inside the channel is reduced from 7000 to 90 G, with a 20 G/in. gradient across the channel opening on the median plane. As close as 5 in. from the outside edge of the coil, the first harmonic introduced is 1.1 G. Without dipole current, the field in the channel is 1560 G with a 16.2 G first harmonic, at the same distance.