Indirectly sensing accelerator beam currents for limiting maximum beam current magnitude

Patent · Sun Jan 01 04:00:00 EST 1995

OSTI ID:870016

Bogaty, John M ^[1]; Clifft, Benny E ^[2]; Bollinger, Lowell M ^[3]

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1. Lombard, IL
2. Park Forest, IL
3. Downers Grove, IL

A beam current limiter for sensing and limiting the beam current in a particle accelerator, such as a cyclotron or linear accelerator, used in scientific research and medical treatment. A pair of independently operable capacitive electrodes sense the passage of charged particle bunches to develop an RF signal indicative of the beam current magnitude produced at the output of a bunched beam accelerator. The RF signal produced by each sensing electrode is converted to a variable DC voltage indicative of the beam current magnitude. The variable DC voltages thus developed are compared to each other to verify proper system function and are further compared to known references to detect beam currents in excess of pre-established limits. In the event of a system malfunction, or if the detected beam current exceeds pre-established limits, the beam current limiter automatically inhibits further accelerator operation. A high Q tank circuit associated with each sensing electrode provides a narrow system bandwidth to reduce noise and enhance dynamic range. System linearity is provided by injecting, into each sensing electrode, an RF signal that is offset from the bunching frequency by a pre-determined beat frequency to ensure that subsequent rectifying diodes operate in a linear response region. The system thus provides a large dynamic range in combination with good linearity.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL
• DOE Contract Number: W-31109-ENG-38
• Assignee: University of Chicago (Chicago, IL)
• Patent Number(s): US 5440210
• OSTI ID: 870016
• Country of Publication: United States
• Language: English

Related Subjects

/315/348/
accelerator
accelerator beam
associated
automatically
bandwidth
beam
beam accelerator
beam current
beam currents
beat
beat frequency
bunched
bunches
bunching
capacitive
charged
charged particle
circuit
combination
compared
converted
current
current limit
current limiter
current magnitude
currents
cyclotron
dc
dc voltage
dc voltages
detect
detected
developed
diodes
directly sensing
dynamic
dynamic range
electrode
electrode provides
electrodes
enhance
ensure
event
exceeds
excess
frequency
function
independently
independently operable
indicative
indirectly
inhibits
injecting
limiter
limiting
limits
linear
linear accelerator
linear response
linearity
magnitude
malfunction
maximum
medical
narrow
noise
offset
operable
operate
operation
output
pair
particle
particle accelera
particle accelerator
passage
pre-determined
pre-established
produced
proper
provided
provides
range
rectifying
reduce
references
region
response
rf
rf signal
scientific
sense
sensing
sensing electrode
signal
signal indicative
signal produced
subsequent
tank
tank circuit
treatment
variable
verify
voltage
voltages