Eric Björklund LANSCE-8 Controls Software (LA-UR-05-2848)

LANSCE Master Pattern GeneratorLANSCE Master Pattern GeneratorLANSCE Master Pattern GeneratorLANSCE Master Pattern Generator


Eric Björklund

LANSCE-8 Controls Software

(LA-UR-05-2848)


Features of the LANSCE Timing System

• 96 Timing Gates.– Centrally Generated.– Distributed on Coax and Fiber From MPG.

• 120 Hz Operation.• Machine cycle is 8.222 milliseconds.

– Start of cycle synchronized with AC Line crossing(positive and negative slope).

– Timing Gates Clocked by 2.8 Mhz Ring Revolution Frequency.

• 1 Second Super-Cycle (120 Cycles).• Versatile (and therefore complex) facility:

– 3 flavors of H- beam– 2 flavors of H+ beam– Single Shot & Continuous Mode Capability for Any Beam Flavor.


Special Requirements (Mostly Age-Related)

• Reliability is important.– It can take up to 2 hours to recover from a 1 second loss of

RF-gates.

• Evenness is also important.– Absolute requirement for some gates:

• RF gates• Neutron Choppers

– Less of an issue for other gates:• Isotope production• Single-Shot experiments• Irradiation Experiments


Current Architecture of LANSCE Timing System

• Star configuration

• 4 redundant gate generator sets in 2 CAMAC crates.

• Gate generators are loaded by Master Timer computer, then run independently.

• Master Timer computer checks the output of the gate generators and automatically switches to another set when a discrepancy is seen.

RICE

CAMAC

ISS DATACONCENTRATOR

RICE

CAMAC

ISS DATACONCENTRATOR

Master Timer

MUX

TimingDistribution

Timing Gates

TimingGate

Generators


Tools To Generate the Pattern – Delay and Width

• LANSCE uses a rule-based system to generate the placement of timing gates within a machine cycle.

• Configuration file contains rules for either automatically setting a gate’s delay and width, or providing limits on acceptable values.

• A special parser reads the configuration file and generates a subroutine that is compiled and linked into the MPG program.

;; Low Frequency RF Gate ; M(LFRF) = 30 D(LFRF) = D(LBEG) - 400 E(LFRF) = D(SREX);; Storage Ring Extraction Window; M(SREW) = 30 D(SREW) = E(LBEG) - 50 E(SREW) = D(EKLF);; Storage Ring Extraction Gate; M(SREX) = 30 D(SREX) > D(SREW) + 50 L(SREX) = 10;; LANSCE Chopper Synchronization Gate; RR(LSYC) = 20 D(LSYC) = D(T0) - 100 E(LSYC) = D(EKLF) + 125;; LANSCE Fast Chopper Synch Gate; RR(LFCG) = 120 M(LFCG) = 0 D(LFCG) = D(EKLF) L(LFCG) = 25


Tools To Generate the Pattern – Super-Cycle Layout

• “Mode” rules determine which gates may occur on which machine cycles.

• Cycles are assigned based on requested rep-rate and mode constraints.– Keep the three H- flavored gates on separate cycles.– Keep the two H+ flavored gates on separate cycles.– Keep the high-power H+ flavored gates and high-power H- flavored gates on

separate cycles.

• Prioritizes order in which gates are assigned.

Mode Name Base Gate Definition

0 ANY None May occur on any cycle

1 201 PREDECESSOR 201RMay only occur on cycles preceding 201R gates

2 805 PREDECESSOR 805RMay only occur on cycles preceding 805R gates

3 RFAL PREDECESSOR RFALMay only occur on cycles preceding RFAL gates

4 RFAM PREDECESSOR RFAMMay only occur on cycles preceding RFAM gates

5 RFAS PREDECESSOR RFASMay only occur on cycles preceding RFAS gates

6 201 COINCIDENT 201RMay only occur on cycles with 201R gates

7 805 COINCIDENT 805RMay only occur on cycles with 805R gates


Tools To Generate the Pattern – Super-Cycle Layout

• Theoretical Framework Developed for Evenly Distributing Gates Across the Super-Cycle.

– Completely even distribution for unconstrained gates with rep-rates that evenly divide 120.O(n) time.

– Most even distribution possible for unconstrained gates with rep-rates that do not evenly divide 120.O(n) time.

– Most even distribution possible for constrained gates whose “ideal” patterns map into the available cycles.O(n2) time.

– Good heuristics for constrained gates whose “ideal” patterns do not map into the available cycles.O(n) – O(n5) time.

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Tools To View The Generated Pattern

• “Micro” view of a single “generic” cycle.

• Shows gate relationships within the machine cycle.

Time Plot


Tools To View The Generated Pattern

• “Macro” view of the Super-Cycle.

• Shows which gates are assigned to which cycles.

Rep-Rate Plot

Eric Björklund LANSCE-8 Controls Software (LA-UR-05-2848)

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