Dynamics of Linear Accelerator; DYNAMIQUE DE L'ACCELERATEUR LINEAIRE

Technical Report · Fri Oct 31 04:00:00 EST 1958

OSTI ID:4335477

Hoyaux, M

The linear acceleration of charged particles has been studied in as general conditions as possible, on the viewpoint of small oscillations around the principal motion.'' The following results have been obtained. With a single travelling TM wave, phase stability and radial stability are not compatible. However, it is possible to catch electrons in phase with a single TM wave travelling with the speed of light. The phase tends asymptotically towards a limit value as the inverse square of energy; the beam expands radially as the logarithm of energy. Radial stability of an electron beam can be obtained by means of a longitudinal magnetic field. The beam radius remains approximately constant. For heavy particles, the field values are much too high. Long acceleration through a sequence of thin electrostatic lenses is impossible. At first order, phase stability and radial stability are uncompatible. In a very narrow and rapidly decreasing phase range, second order terms correspond to compatibility conditions, but the heam expands as the power (3/8) at least of energy. In the general case of a superposition of TM travelling and/or stationary waves, the exponent (3/5) may sometimes be replaced by (1/2), but at the same time, defocusing parasitic effects appear. Radial stabilization by means of thin foils or grids corresponds to a radial expansion of the beam as a power of energy comprised betwoeen (3/8) and (1/4). In the Berkeley device, the minimal value is attained. The acceleration through a sequence of independent cyclindrical cavities in TM/sub olo/ mode corresponds to a contraction of the beam as the power (--1/8) of energy: but such a device is only practical for electrons. Radial stabilization by means of a coaxial structure with a d-c current in the linner part parallel to that of the beam corresponds to a radial contraction of the beam as the power (--1/8) of energy, but currents in excess of 10,000 amps are required in the case of heavy particles. Radial stability by means of a coaxial structure with d-c convenient bias allows the maintenance of the beam radius constancy. The d-c bias is at least 10,000 volts in the case of heavy articles. In every case, the amplitude of phase oscillations decreases as the power (--3/4) of time. Energy transfer is possible from phase to radial oscillations if the ratio between frequencies is even. The ratio (2/1) seems the most dangerous. (auth)

• Research Organization: Ateliers de Constructions Electriques de Charleroi. Centre Nucleonique, Belgium
• NSA Number: NSA-12-007537
• OSTI ID: 4335477
• Report Number(s): NP-6631
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

CHARGED PARTICLES
CONFIGURATION
CURRENTS
ELECTRIC POTENTIAL
ELECTRON BEAMS
ELECTROSTATICS
ENERGY
FOILS
FREQUENCY
ION BEAMS
LENSES
LINEAR ACCELERATORS
MAGNETIC FIELDS
MASS
MOTION
NUMERICALS
OSCILLATIONS
PHYSICS
STABILITY
VELOCITY